Paul J. White

Heads, Tails, and Decisions In-Between: The Archaeology of Mining Wastes

Ore dumps, milling wastes, and other processing residues are ubiquitous features of mining landscapes and often dominate the surface remnants of former operations. While archaeologists have yet to investigate these features systematically, state and federal hazard mitigation programs increasingly target mining and milling wastes for environmental testing and cleanup. This article investigates the extent to which these deposits retain historical information, including differences in ore bodies and technological processes, by reviewing historical and contemporary literature and analyzing rock and sediment samples associated with a small-scale gold mine in Alaska for which an excellent documentary record exists. Results of physical and chemical analyses are tempered by the variability caused by sampling methods, testing techniques, and post-depositional processes, but promising avenues for future studies are also identified.

Introduction

With public opinion polls ranking mining as North America's least-favored industry, below even that of tobacco manufacturers, mining enterprises have seemingly gained a reputation more for their undesirable consequences than for their desirable products.¹ Processing wastes are the likely source for much of this discontent. According to the Environmental Protection Agency (EPA), mining operations in the United States generate some two billion tons of waste material annually, accounting for up to 40 percent of the nation's solid waste. Approximately three-quarters of mining refuse comes from materials overlying mineral deposits, with the remainder classified astailings—the discard from milling processes employed to concentrate ore values. Generally speaking, the ratio of waste to product is greatest in the working of precious metals because high commodity prices enable companies to work comparatively poorer outcrops. By recent estimates, the production of a single gold ring now leaves in its wake any-where from 3 to 35 tons of mine waste.²

There is little need to account for where the bulk of this material ends up. Vast, barren piles of processed rock tend to dominate mining sites, and they also form some of North America's most dramatic industrial landscapes. Beyond their often-arresting appearance, environmental testing indicates that mining wastes contribute to an unwelcome legacy of contamination, impacting mining regions long after the demise of operations. Indeed, wastes at historic and abandoned mines are thought responsible for a large portion of the total pollution stemming from mining wastes, a reflection of their creation during periods when environmental regulations were poorly enforced, comparatively lenient, or entirely nonexistent.³ To remedy this problem, government programs have increasingly slated wastes at abandoned mines for hazard mitigation over the last three decades.

The exponential growth of cleanup activity has sparked a proliferation of technical data on the sources, types, and extent of mine waste pollution. That little of this information has found its way into historical analyses is unfortunate and the likely consequence of a frequent communication divide between environmental and cultural resource practitioners. There are, however, good reasons to explore this area further. Industrial archaeologists generally consider process residues a promising source of information because of their "quantity, usually undisturbed pattern of distribution, and potential for physical analysis."⁴ Archaeological investigations of iron-making wastes, among the most studied of industrial residues, have productively linked physical and chemical variances in slag composition to different reduction processes, stages within a process, and, more tentatively, operative efficiency.⁵ Admittedly, the extent to which an archaeological study of mining wastes could harvest similar yields is difficult to assess a priori. If other studies of wastes suggest profitable directions, clear evidence of the permeability and reactivity of overburden, ore dumps, tailings, and other mining sediments indicate that mining wastes are more problematic storehouses of historical information.

To assess the historical information potential of mining wastes in greater detail, this article presents a review of past findings together with the results from environmental characterization and limited archaeological testing in Alaska's Bremner District. This small-scale gold mining region (figure 1), with lode mines active from the mid-1930s to early 1940s, features excellent physical and documentary preservation that provides specific information about the changes taking place during operations. The comparison of different data sources permits the evaluation of several mining deposits (including ores from different mines, ores delivered to the mill [heads], sediments remaining within the mill, and mill tailings) in terms of their information potential. These are examined here with an eye to identifying historical associations, interpretive problems and directions for future research.

Figure 1. Alaska's Copper Basin, showing location of the Bremner District and places mentioned in text.

Mining Wastes as Archaeological Artifact? Prospects and Pitfalls

Processing wastes, at first glance, may appear an unlikely source of information about past mining operations: dumping locations, whether immediately outside mine entrances or downhill of mill sites, suggest little more than a governing economic rationale to dispose of wastes as quickly as possible. Wastes are, however, fundamentally cultural deposits. As environmental historians have frequently stressed, dumping practices have changed over time, and these practices are often in line with prevailing cultural attitudes about the environment.⁶ Waste deposition required both forethought and continued expenditure, and mining engineers employed different strategies to improve the efficiency of waste disposal. Until the late-19th century, and continuing in remote districts through the 20th century, mining engineers preferred to locate milling facilities along watercourses to expedite waste removal.⁷ The sedimentation and contamination of streams resulting from these practices increased in severity with the growing capability of milling techniques to process poorer deposits. By the early-20th century, and in response to rising conflicts between mining operations and downstream users, anti-debris legislation in several western states required mining operations to impound their wastes.

Local conditions influenced the choice of containment methods. For operations located in rugged terrain, the construction of a retaining wall across the floor of the valley to trap mine wastes might have sufficed. Milling plants located on level or gently sloping ground required other alternatives. Here, the use of size-separating devices, such as classifiers, dewaterers, or perforated launders, enabled engineers to stack tailings and also to construct impoundment dams entirely from tailings material, the larger, sand-size particles forming the embankment behind which finer particles, or "slimes," were directed.⁸ Other companies found new uses for wastes, including as fertilizer, road and railroad gravel, concrete aggregate, and fill for mine stopes. Waste storage also opened possibilities for waste reprocessing if improvements to milling technology or mineral prices warranted. In preparation, some companies separated mining and milling wastes according to grade.⁹

Mining literature also indicates that wastes contain internal information of import to daily operations. Ore bodies were rarely homogenous and often changed with depth—and the profitability of mining ventures hinged upon the ability to keep apace of these changes. Mine operators accomplished this by regularly sampling ores and host rock. Inside milling plants, too, the comparison of mill heads, concentrates, and tailings enabled millwrights to calculate the efficiency of the plant and of individual machines.¹⁰ Supporting the textbook dictum that "a millman is not progressive who is content with his flow sheet," mining treatises and journal articles abound with case studies identifying minor improvements to extractive efficiency. Some common adjustments included altering grinding size, varying the chemical agents used in recovery equipment, rerouting the flow of ore through the mill, or adding and removing machines from the circuit.¹¹

Hypothetically, the physical and chemical composition of mining wastes should record some of these transformations (Table 1). Some indications of this potential are indeed discernable from accounts of companies reworking milling wastes as an ore body, the historical characterization of tailings at the Sweeny mill near Kellogg, Idaho, providing a good case in point. Waste characterization work, conducted shortly after the mill's closure in 1918, involved trenching the tailings at several locations. Chemical analysis of these sediments identified four successive dumps, with later dumping episodes found to be poorer in lead and silver concentrations—a circumstance that the project's author attributed to improved milling methods.¹²

Table 1. Historical Processes with Potential Signatures in Mining and Milling Wastes

Mining Waste
  • Changes in the ore body or host rock
  • Separation of mined materials by grade

Milling Waste
  • Changes in the ore body
  • Processing of different ore bodies
  • Separation of wastes by grade
  • Residues of milling processes
  • Changes in milling techniques and/or grinding size
  • Overall recovery efficiency

Within Milling Facility
  • Residues of milling processes
  • Recovery efficiency of particular machines

While such studies are encouraging, greater difficulties face those wishing to interpret long-abandoned wastes. Chief among these is that tailings and mine waste piles continue to be key sources of pollution in mining regions. Acid rock drainage, by far the most prevalent problem, is induced by the oxidation of sulfide minerals commonly found with metal ores. The weathering of sulfides generates sulfuric acid that corrodes other minerals as it percolates through the deposit. Two common environmental ramifications of this process are the lowering of pH levels in nearby watercourses and the introduction of a range of metals (such as arsenic, cadmium, and iron) into solution at high concentrations. Acidic drainage is not limited to waste deposits; research indicates that unworked outcrops can also generate acid and release metals in concentrations violating water quality standards.¹³ Even so, tailings and mine waste present especially acute problems because their finer particle size creates greater surface area for oxidation.

Acid rock drainage does not modify deposits uniformly. Waste characterization studies indicate that local depositional environments influence significantly the rates and extent of acid generation and metal leaching. Acid attacks minerals differently; quartz and feldspars, for instance, react weakly in acid and tend to decompose at extremely slow rates, while the presence of carbonates can neutralize acid and limit the mobility of heavy metals. Oxidation decreases with depth and is also influenced by general climatic conditions. Weathering rates are faster in warmer and more humid climates, and mul-tiyear studies indicate that metal loading surges in streams during and immediately after rainstorms. Common strains of bacteria are also known to increase oxidation rates considerably.¹⁴

Despite these significant problems, there are still indications that long-abandoned mining wastes retain serviceable information about past operations. Although sporadic, archaeological investigations of mining wastes have identified some positive connections. Soil samples collected during the excavation of an early-19th-century mill at the Reed Gold Mine, North Carolina, for instance, found mercury concentrations well above natural levels, indicating its use in the milling process. The testing of soils during investigations at a 19th-century borax works in Death Valley, California, indicated that the earliest steps of the recovery process were most successful in extracting borax. Researchers also identified high borax concentrations within some wastes, possibly representing harvested deposits that had escaped reprocessing.¹⁵ Other indications come from environmental testing programs. Testing at an EPA cleanup site in Arizona, for instance, discriminated zones of different ore types across the tailings pond, consistent with the mill's operation as a custom facility.¹⁶

Further archaeological attention to mining wastes is timely, given the rapid expansion of environmental characterization programs over the last few decades. The EPA's "Superfund" program—the most recognized of all government initiatives—targets the gravest cases of contamination, with cleanup sites varying in scale from individual mines to entire watersheds containing well over 100 abandoned mines.¹⁷ Remediation work is also conducted by agencies operating under the Department of the Interior's Abandoned Mine Lands pro-gram, an initiative that aims to coordinate the cleanup of federal lands impacted by acid rock drainage. As part of these efforts, the Bureau of Land Management has inventoried 10 percent of the approximately 70,000 mining sites estimated in its holdings. Of those sites surveyed, the agency reported 6,650 (96 percent) as posing safety hazards and 890 (13 percent) as presenting significant environmental threats.¹⁸ The U.S. Forest Service estimates that anywhere from 20,000 to 50,000 mines are generating acid on lands within its jurisdiction, impacting up to 10,000 miles of water drainages. Proposed legislation, entitled the Abandoned Hardrock Mines Reclamation Act, was introduced to the House of Representatives in January 2003. If passed, this act will provide funds to states for completing an inventory of abandoned mine lands, setting aside $45 million per year for mine cleanup work.¹⁹

The rapid increase in mine cleanup activities has raised significant historic preservation concerns. In part, waste mitigation often occurs in tandem with remedying other safety concerns, such as mine workings, and too often this is conducted without consideration for historical value.²⁰ The historic preservation movement has also developed strong interests in the interpretation and protection of historic cultural landscapes, and cleanup strategies cannot avoid manipulating these to some degree, whether by aggregating waste into one area, recontouring profiles to lessen surface erosion, capping tailings with soil and vegetation, or, in extreme cases, removing wastes to offsite storage.²¹ In this light, proposing that mine wastes might be a partial record of the mine and tailings a partial record of the mill might generate another area of conflict. On the other hand, environmental studies have examined mining wastes more extensively than archaeological research to date, with testing programs regularly involving the collection and analysis of multiple samples from different areas around the mine and from within individual deposits. Certainly, data from environmental characterization comes with important limitations for historical analysis. Environmental studies are designed to furnish information about current, not historical, conditions, bringing with them different methodologies. But if characterization data is unlikely to procure all the information that archaeologists may want to learn from mining wastes, it is still a pragmatic place to start.

Mining and Milling in the Bremner District, Alaska

For those visiting the Bremner District today, the available travel options differ little from those facing miners in the 1930s: either travel across frozen rivers by snowmobile or sled, or fly by two- or three-seater plane during the summer months. Similar to many northern gold districts, this small-scale gold mining region, located in Alaska's rugged Chugach Range (figure 1), was neither easily accessible nor particularly profitable. Climatic conditions restricted mining activities to a four- to five-month working season. Despite nearly a century of intermittent operations, miners ultimately won less than 5,000 troy ounces of gold from the area's streambeds and rock outcrops, a quantity that, at best, granted a working wage to some of those who sought profits.²² If operations were short-lived, signs of past mining activity nevertheless remain conspicuous. Rock and snow slides have obliterated some structures, but several camp buildings are still standing. Electric power and road networks are traceable along the valley floor, as are the routes of aerial tramways to the mines. Waste dumps are identifiable at mining sites and at a milling facility built to process the district's ores. Equipment and supplies are distributed throughout the valley, including a dump truck once used to relay ore from the tram bunkers to the mill and that now sits on blocks outside the camp garage (figures 2 and 3). The survival of a range of company records, including stockholder reports, survey maps, company inventories, a manager's diary, and historic photographs, complements this rich physical preservation. In combination, these evidentiary sources enable detailed insights into the nature of operations, including changes in the ore bodies and modifications to milling techniques (summarized below)—offering a prime opportunity for evaluating the historical potential of environmental data collected recently from the district's mining sites. Lode mining activity in the Bremner District began in earnest in 1927, when prospector S. Lee Ramer staked 12 mining claims at the headwaters of Golconda Creek. Shortly after Ramer's discovery, another prospector, Charles Nelson, located a promising vein at significantly higher elevation and approximately one mile to the north. According to geological reports, both quartz veins were mineralized in places by iron sulfides—including chalcopyrite, galena, pyrite, and sphalerite (respectively copper-iron, lead, iron, and zinc sulfide)—and flecked with gold. In 1931, Lee Ramer and his brother Peyton formed the Bremner Gold Mining Company and set out to transform both the Lucky Girl and Grand Prize prospects into a working mine (figure 4).

Figure 2. Blacksmith shop, garage, and dump truck at the Yellow Band Gold Mines camp. The excellent condition of many structures in the district is due to Paul Fretzs's upkeep of mine buildings during the 1970s as well as to recent National Park Service preservation efforts. Photograph by author.

Figure 3. Fortunate in name but not in destiny, the Lucky Girl mill suffered a direct hit from a snow slide sometime in the 1970s. The slide toppled the jaw crusher into the ore bin (foreground), upturned the classifier (just above the ball mill at photo center) over the Wilfley table, and redeposited the mill's superstructure on the valley floor up to one-quarter mile from the mill site. Surprisingly, most milling machinery remains in its original position. View looking southeast. Photograph by author.

Figure 4. Lode mines in the Bremner District, c. 1939, indicating aerial tramlines and haul roads connecting the mines to the company camp and Lucky Girl mill.

Several economic conditions lessened the exorbitant transportation costs that operators in the Bremner District had formerly faced. Regionally, mining enterprises in the Copper Basin benefited from a 200-mile-long railroad completed in 1911 that connected the port of Cor-dova to the Kennecott Copper Mines (30 miles northeast of Bremner). The Ramer brothers benefited also from the growth of McCarthy and Chitina as supply centers and the burgeoning availability of aerial transportation services—the latter bringing substantive reductions to the time and costs of transporting equipment, supplies, and workers.²³ Moreover, and in contrast to the fate of most industries during the Great Depression, federal policies to amass gold bullion enabled gold mining operations to take advantage of lowered supply costs and high labor availability.²⁴The most explicit government endorsement came with the passage of the Gold Reserve Act (1934), which fixed gold prices at a new high of $35 per fine ounce and required the treasury to purchase all nationally produced gold. That year, the Bremner Gold Mining Company secured a loan to finance the construction of major surface improvements. In addition to improving camp facilities, workers improved an airstrip at the headwaters of Golconda Creek and installed an aerial tramway at the Grand Prize Mine to connect the mining activities with operations on the valley floor. One-half mile south of the Lucky Girl claims, the company constructed a hydroelectric plant to power operations. Adjacent to the Lucky Girl Mine, the company cleared a site for the construction of a small-scale mill capable of processing up to 50 tons of ore per day.²⁵ Despite the sizable financial investment—the cost of milling equipment alone reaching $50,000—this pilot plant enabled the company to reduce gold ore directly to bullion, promising significant savings on transportation costs.²⁶

The layout of the Lucky Girl mill followed a fairly simple design of ore reduction and gold recovery that required one operator to run (figure 5). In common with contemporary milling practices, ore reduction occurred as a two-stage process. Material entering the mill building passed first over a "grizzly" (a set of parallel bars serving as a rough sorting device) and then into a "jaw crusher." The crusher worked ore between a moving plate or "jaw" and a fixed plate, breaking it into 1–1/2-inch diameter pieces and letting crushed material drop into a bin set below the machine. Secondary crushing took place in a ball mill. This large, revolving cylinder used cast-iron balls to pulverize the ore until it was fine enough to pass through an output screen. The mill operated in tandem with a classifier (a mechanical sorting device) that improved the consistency of the product by directing heavier materials back to the ball mill for further grinding. Upon reaching the desired milling size—here, the consistency of medium sand—ore entered into the recovery circuit, where machines separated out valued material from wastes.

Figure 5. Lucky Girl mill, c. 1941. The stepped layout of the building—a popular design feature of 19th- and early-20th-century milling plants—enabled gravity alone to move material through the milling circuit. Reconstruction based on 1998 field documentation by Patrick Martin and the author.

Gold recovery at the Lucky Girl mill used both amalgamation and gravity concentration techniques, a tried-and-true combination popular among small-scale operators.²⁷ Amalgamation extracted gold chemically by inducing the formation of a mercury-gold alloy. The milling circuit included two such recovery devices. A mechanical "amalgamator" positioned immediately after the ball mill mixed the ore with water and mercury in a small chamber, with amalgam collecting on mercury-coated copper plates placed inside the device. The company also installed amalgamation plates into the bottom of launders positioned after the amalgamator and classifier. In accordance with general practices, the mill attendant periodically scraped the "pasty" amalgam collecting on the plates and took the consolidated mass to the mine's assaying furnace for further reduction into bullion.

Ore passing through the amalgamation circuit continued to the lowest level of the mill for final processing on a Wilfley table. This gravity concentration device consisted of an inclined tabletop fitted with riffles (wooden slats) and over which the slurry of ore was introduced. In operation, the table separated mineral grains according to differences in specific gravity (approximated by the maintenance of a uniform feed size). Lighter particles, such as quartz, flowed over the riffles and off the long edge of the table, dropping into a waste launder and passing out of the mill building. Riffles caught the heavier particles, and the shaking motion of the table conveyed these sediments off the table's short end and into a concentrate bin.²⁸

By most indications, the Bremner Gold Mining Company should have enjoyed a production run of several years, for, contrary to the history of many gold mines, the company had invested years in property examination and scaled mining infrastructure to an early phase of exploration. Indeed, initial outward measures of the operation were generally positive. Over the next few years the company employed a workforce varying from one- to two-dozen workers—respectable numbers for a small-scale mine. At times, the mill ran eight-hour shifts back to back, and by the close of 1936, the mill had processed some 2,000 to 3,000 tons of ore, with ore values averaging a low, but workable, gross return of $10 to $12 per ton.²⁹

Yet miners soon encountered difficulties. As with most metal mines, surface outcrops contained the richest ores and, as workings progressed, miners found only poorer and more chemically complex deposits. Furthermore, the quartz veins in the district tended to pinch and swell and end abruptly, with gold distributed sparsely and in erratic pockets and lenses.³⁰ Outward signs of these troubles occurred as early as 1935 when work ended at the Grand Prize, the mine having procured a meager 500 tons of ore for the mill. By summer 1936, spotty and decreasing ore values were also evident on the Lucky Girl vein. In 1937, the Bremner Gold Mining Company devoted efforts to tapping the vein at a lower elevation, but results proved discouraging (a later analysis of the tunnel concluded that the engineer had likely missed the mark by several feet). Having processed all of the ore stockpiled in the previous season, the Lucky Girl mill remained idle during 1937. At the end of that year, the Bremner Gold Mining Company teetered on the brink of collapse, its future bleak, and its finances exhausted.

Instead of marking an end to lode mining in the Brem-ner District, the death throes of the Bremner Gold Mining Company attracted the interest of mining engineer, surveyor, and lawyer Asa Baldwin. He was familiar with both the operations and the locality, having once optioned the Lucky Girl and Grand Prize claims from the Ramer brothers during the late 1920s. Since 1935, Baldwin had investigated an ore outcropping found to the south of the Ramer's claims and on the opposite side of the valley. By 1937, development work on his Yellow Band prospect had marked out three corners of a high-grade block, cautiously estimated to be 80 feet long, 4 to 6 feet wide, and 30 feet deep, with a potential value of $15,000.³¹ In 1938, Baldwin formed the Yellow Band Gold Mines and negotiated successfully for the purchase of all possessions of the Bremner Gold Mining Company holdings and the leasing of another gold prospect, the Sheriff claims, located by Charles Nelson in 1936 (figure 6).³²

Figure 6. The Lucky Girl mill and mine at the time of takeover by the Yellow Band Gold Mines in 1938. The diagonal line of overburden piles (upper left to below photo center) traces the path of the Lucky Girl vein. The lowest of these was formed in 1936–37 as a last attempt to wrest a profit from the vein. The low building to the left of the mill, formerly a dry room, later served as an assaying facility for testing ores and reducing amalgam to gold bullion. Photograph by Asa Baldwin, Asa C. Baldwin Photograph Collection, PCA 71–430, Alaska State Library, Juneau.

The Yellow Band Gold Mines spent the first two years engaged mostly in preparatory work, employing a crew of approximately one dozen workers variously about the mine. If journal entries surviving for one year of the mine's operation offer any indication, the crew worked every day except July 4, when they "Hoisted Old Glory [and] took it easy."³³ By the close of the 1939 season, the list of improvements included relocating the main camp to a more central location, establishing a new airstrip, erecting aerial tramways to the Sheriff and Yellow Band mines, building a mine bunkhouse, and constructing a haul road between the tram stations and the mill. The Lucky Girl mill also received a minor overhaul. In 1938, a millwright ran 20 tons of ore from the Yellow Band Mine through the mill, adjusting the circuit to make improvements to efficiency. One recorded modification involved changing the output screens on the ball mill from 60-mesh to 80-mesh (a change in aperture from respectively 0.0098 inches to 0.007 inches). This improvement permitted finer grinding and ostensibly higher gold recovery, with the tradeoff of reducing the mill's running capacity to 30 tons per day.³⁴ During this development phase, Baldwin aimed for each year's activities to procure at least 500 tons of ore for the mill. No ores came from the Lucky Girl and Grand Prize mines as test samples confirmed a former millwright's opinion that the ore was too low grade to be either mined or milled profitably. The company performed some work at the Yellow Band Mine during the 1938 and 1939 seasons, but by 1940 all mining efforts had shifted to the Sheriff Mine—a move governed partly by a need to reduce annual lease payments (figure 7).³⁵ Gold at the Sheriff Mine tended to be found in association with galena and arsenopyrite (arsenic-iron sulfide); assay results indicated the latter often brought the richest concentrations of gold, with some seams valued at more than $4,000 per ton (figure 8).³⁶ The presence of sulfides, however, did create some difficulties in mill recovery, Baldwin noting that amalgamation did not recover gold from the arsenopyrite ore as readily.³⁷ Two modifications to the gravity-concentration circuit may have been intended as possible fixes. By 1940, if not before, the millwright reintroduced all table concentrates back into the ball mill, with concentrates remaining at the end of the season panned by hand. In mid-1941, Baldwin and the millwright installed frames for "corduroy blankets" (another gold-saving technique) next to the Wilfley table, but there is no indication that they saw actual use.³⁸ Company reports indicate that mill recovery rates steadily improved each season, but that gold lost in tailings doubled in the 1941 season to $1.40 per ton or approximately two parts per million (ppm).

Figure 7. Delivering ore to the Sheriff Mine's tram terminal, c. 1939. The lower tram terminal, where ore samples were collected in 1996 for environmental characterization studies, is located at the toe of a moraine some 5,000 feet distant from the mine and 1,500 feet lower in elevation. Photograph by Asa Baldwin, Asa C. Baldwin Photograph Collection, PCA 71–493, Alaska State Library, Juneau.

Figure 8. Detail of an assay map of the Sheriff Mine, c. 1939, showing variations in vein thick-ness and ore values. Note the occurrence of arsenopyrite, identified as "Arsen Ore" (map center), where gold values ranged from $4,354 to $10,150 per ton. One small square represents one foot. Asa Baldwin, "Assay Map, Sheriff Claims" (see n. 36).

Annual reports also indicate that the company reached its 500-ton quota only once (Table 2). Unusually low production volumes in 1941 were caused by problems in air service that delayed the arrival of miners into the district by a month and also forced work cutbacks on account of depleted food supplies. Perhaps to offset the financial ramifications of reduced development work, a general pattern of decreasing ore tonnage but rising ore values and recovery rates suggests that the company sent only the richest ore to the mill. Irrespective of these efforts, by the end of 1941, with the country now at war, the Yellow Band Gold Mines found itself in a frustrat-ingly similar predicament to what the Bremner Gold Mining Company had faced four years earlier. Confronted with insufficient funds to begin work in the spring, Baldwin sought additional loans.³⁹

Workings remained idle during the 1942 season, and two events in the fall stymied attempts to secure capital for the following year. In September, Baldwin, who had been so instrumental in organizing operations in the district, died of a heart attack. Less than three weeks later, the War Production Board passed limitation order L-208 declaring gold and silver mining a nonessential wartime industry—and thereafter all gold mines had to close within 60 days.⁴⁰ When the order was rescinded in 1945, Claude Stewart, the new company president, made several attempts to rekindle operations. However, depressed economic conditions for gold mining (including stagnant gold prices and rising wage costs) thwarted his efforts. With finances too lean to even visit the mines, Stewart decided that the only course of action left was to interest another company in a buyout. From the late-1950s, Paul Fretzs, one of the company stockholders, arranged to conduct assessment work on claims in return for what he could take out until a new investor was found.⁴¹ Some further cleanup of mine workings and the mill took place, but Fretzs soon resorted to salvaging copper wire from the electric lines to repay development expenses. The company never found a buyer and, in 1980, the property became incorporated into the 13.2 million-acre Wrangell-St. Elias National Park and Preserve. Tellingly, in 1975 Fretzs conceded, "Yes, I have really tried to make Yellow Band work, but it is impossible"—capturing in a few words the labored experience of most entrepreneurs in the district.⁴²

Table 2. Milling Record of the Lucky Girl Mill, 1935–1941^a
Year	Tons Milled	Ore Source^b	Av. Value Mill Heads	Av. Value Tailings	Recovery	Gross Production
Bremner Gold Mining Company
1935 1936 1937	1,500 1,000 —	L 67%; G 33% L —	$10-$12 $10-$12 —	— — —	— — —	< $18,000.00 < $12,000.00 —
Yellow Band Gold Mines, Inc.
1938 1939 1940 1941	20 505 461 262	Y S 96%; Y 4% S S	$20.00 $9.16 $20.13 $46.45	$1.98 $0.70 $0.72 $1.40	91% 93% 97% 97%	$400.00 $4,626.60 $9,279.37 $12,170.90
^a Derived from mine inspector's report (see n. 25) and annual reports of the Yellow Band Gold Mines to stockholders for years 1938–1941 (see n. 32, 34, 39). Italicized figures are author's estimates. ^b G: Grand Prize Mine; L: Lucky Girl Mine; S: Sheriff Mine; Y: Yellow Band Mine.

Environmental Characterization and Archaeological Investigations at Bremner

A decade after the Bremner District's inclusion into a National Park, cultural resource managers initiated several hazard mitigation measures to improve visitor safety. Park staff systematically removed a range of hazardous materials, including batteries, fuel, fuses, dynamite, and blasting caps. Remediation teams also closed mine openings and slackened aerial tram cables to reduce hazards to aircraft. In 1996, geologists from the National Park Service and the United States Geological Survey (USGS) visited the Bremner District as part of a broader sampling program to assess potential environmental hazards at several metal-mining sites in the park. At Bremner, researchers collected water and stream sediment samples from several locations, including from a stream exiting the Lucky Girl Mine, from a stream below the mill, and from more distant streams. Rock samples were collected from the surface of dumps at or associated with the Grand Prize, Lucky Girl, Sheriff, and Yellow Band mines and from mill tailings.⁴³ In total, researchers collected 36 samples from 14 locations in the Bremner District.

As with other characterization studies, sampling strategies in the field and in the laboratory were critical considerations in project design, in no small part because chemical analyses generally do not require large samples (some techniques used in this study needing less than a gram). To improve sample representativeness, USGS testing in the Bremner District collected rocks and sediments as composite samples—a method involving the collection of 20–30 individual samples at each test site. In the laboratory, sediment samples were air dried and sieved to 80-mesh, with the sieved fraction then pulverized to a fine flour consistency and an approximately 185-gram portion saved for chemical analysis. Rock samples were crushed to pea size, passed through a sample splitter, with a 185-gram portion then pulverized and saved for analysis. Researchers collected water samples by sampling at intervals across stream widths.⁴⁴

Laboratory testing subjected samples to several analytical techniques in order to determine a broad range of element concentrations. Two of the most used methods were inductively coupled plasma-atomic emission spectrometry (its welcome acronym, ICP-AES), valued for its high sensitivity and capability of detecting up to 40 elements simultaneously, and atomic absorption spectrophotometry (AAS), used to determine concentrations for select elements such as mercury and gold.⁴⁵ As with site sampling strategies, laboratory testing took analytical duplicates to check results.

The principal concern of geochemical testing was to investigate the impact of mining locations on nearby watercourses. Water and stream sediment samples from the Bremner District did not show signs of acid runoff and metal leaching; pH levels were near neutral, and metal concentrations did not exceed environmental standards. However, a test for acid runoff (simulated by mixing samples with acid and analyzing the leachate) indicated a more complex situation among other sediments.⁴⁶ Tailings leachates were acidic (pH 4.2), likely from the decomposition of pyrites known to have been distributed liberally in the district's gold-bearing ores. The acid also mobilized metals, and tailings leachates contained high concentrations of arsenic, iron, manganese, and relatively elevated levels of gold, lead, and silver. Conversely, samples collected from waste dumps outside the Lucky Girl and Yellow Band mines showed close to neutral pH levels (8.3 and 8.7) and low metal mobility, with leachates containing elevated levels of aluminum and tungsten but no other excesses. From these results, researchers concluded that water coming off the tailings probably carried metals during spring runoff, but that any metal loading would be highly localized due to the small volume of mill tailings and rapid dilution by adjacent streams.⁴⁷

The analysis of rock and sediment samples generated data useful for geological characterization, but it also raises questions of potential value for historical analysis: Can ores from specific mines be distinguished? To what extent are historic milling processes visible? How variable are milling sediments? To explore this potential further and improve the scope of historical interpretations, in 2001 additional samples of waste deposits were taken at the Lucky Girl mill. Archaeological investigations, conducted by the author, sought initially to expose a vertical profile of tailings for stratigraphic sampling. To achieve theoretically the greatest representation of all mill periods, a test unit was positioned alongside the lowest mill level directly in front of the waste launder. While this was presumably the point where tailings were ejected, debris from a slide that had hit the mill building in the 1970s obscured the area immediately downhill from the mill site with a surface scattering of rocks and building debris (figure 3). Frus-tratingly, excavations did not locate tailings deposits beneath the slide debris, even though the unit was excavated to bedrock, 1.5 meters below the surface.⁴⁸ Tailings were sampled, however, from a surface exposure interspersed with rock debris located further down the hillside (30 m south from the first unit). Here, tailings were sampled vertically from two lenses located at 5–10 cm and 10–15 cm below the ground surface. In addition to the two tailings samples, samples were also taken of materials found in bins throughout the mill, including from the ore bin, ball mill feeder, classifier oversize, and table concentrates (figure 9).

Figure 9. Sample locations at the Lucky Girl mill during the 1996 and 2001 seasons. Tailings samples 4 and 5 are vertical samples, taken from, respectively, 5–10 cm and 10–15 cm below the ground surface.

To aid the comparison of results and reduce potential sources of variability, where possible, collection techniques followed procedures of the 1996 USGS study. As one notable exception, tailings samples were not taken as composites but intentionally sampled within a stratum. As two variances in laboratory preparation, sediment and rock samples were oven dried (at 60° C) and not sieved prior to pulverizing. ICP-AES and AAS techniques were, however, used to determine elemental composition, as well as X-ray fluorescence (XRF) for preliminary characterization purposes.⁴⁹ Supplementing these techniques, laboratory analysis also included wet-sieving a portion of tailings and milling sediment samples to determine particle size ratios.

The following three sections present data collected from rock and sediment samples during both field seasons. Ore samples collected in 1996 are first examined to discern differences among mine locations and determine a probable source for ores recovered from the mill bin. The elemental profiles of sediments sampled from within the milling circuit are next reviewed to observe the signatures of historical technological processes. Lastly, tailings from both field seasons are investigated to assess factors of internal variability and the correspondence of elemental profiles to historic milling processes.

Table 3. Elemental Composition of Mine Ore Samples (ppm)^a
Element^b	Lucky Girl	Grand Prize	Sheriff	Yellow Band	Mill Bin
Aluminum Arsenic Barium Bismuth Calcium Cerium Chromium Cobalt Copper Gold Iron Lanthanum Lead Lithium Magnesium Manganese Phosphorus Potassium Silver Sodium Strontium Titanium Vanadium Zinc	4,000 10 35 14 130 <5 2 <2 820 7.5 10,000 <2 290 21 260 19 <50 1,800 11 110 <2 90 5 280	10,000 <10 81 69 3,400 12 2 8 1500 2.2 20,000 6 860 8 2,700 160 140 3,000 18 710 83 190 16 200	15,000 380 95 <10 19,000 6 18 3 21 4 14,000 3 65 8 4,900 580 2500 1,300 2 4,200 140 530 32 35	60,000 11 1000 16 6,300 33 66 4 140 6 34,000 16 590 17 10,000 440 500 23,000 6 11,000 180 2,700 93 610	810 810 25 <10 1,600 <5 <2 <2 37 9.8 1,000 <2 270 3 120 43 <50 300 2 110 17 <50 <2 39
^a Data from Eppinger et al., "Geochemical Data for Environmental Studies of Mineral Deposits" (see n. 43), samples 6BR002R, 6BR003R1, 6BR010R, 6BR012R, 6BR014R1. ^b All elements analyzed by 40-element ICP-AES total digestion, except gold, analyzed by graphite-furnace AAS. Elements not represented in table if no concentrations were greater than 1 ppm or if more than two concentrations between mines were below detection limits.

Mine Ores and Mill Heads

Elemental analysis identified low gold concentrations among all ores sampled, the highest concentrations (9.8 ppm or $8 per ton in Depression-era prices) coming from ores found in the mill bin (Table 3). ICP-AES did not test for sulfur, but high iron concentrations in all ores imply the presence of pyrites that miners commonly found with the gold-bearing quartz. Beyond identifying these general characteristics, elemental characterization generally affirms historical assessments made of ores at specific mines. High arsenic levels in the Sheriff ores, for instance, suggest the presence of arsenopyrite noted variously in annual reports, diary entries, and assay maps of the mine. Similarly, the comparatively high concentrations of copper, lead, and zinc in samples from the Lucky Girl and Grand Prize mines allude to the presence of chalcopyrite, galena, and sphalerite observed historically by geologists and mine inspectors at these locations.⁵⁰ Elevated concentrations of these same elements in ore samples from the Yellow Band Mine may also indicate the presence of similar metallic sulfides.

Ore processed in the mill came from the Lucky Girl, Grand Prize, Sheriff, or Yellow Band mines; outside of a few undeveloped prospects, no other lode mines existed in the Bremner District. The visual inspection of mill ore samples collected during the 1996 field season suggests a good fit between ores from the mill bin and ores from the Sheriff Mine, namely through the presence of arsenopyrite in both samples (a mineral evidenced at no other mine).⁵¹ Elemental analysis adds support to this assessment in that low arsenic concentrations occur across all other oresexcept those retrieved from the Sheriff Mine and ore bin, and that both ores are also notably poorer in copper and zinc. Even so, identifying the source of milling ores from elemental analysis alone is problematic. In part, mill ores are lower in most element concentrations than those sampled from the mine, with three elements—aluminum, iron, and potassium—differing in concentration by an order of magnitude. Possibly, these differences fall within the range of variation for a given ore deposit. Leaching may also be a contributing factor, given that samples taken from the mill bin had already passed through the primary crushing stage, and the smaller the particle size, the greater the surface area for oxidation.

Milling Processes

Sediments sampled from within the mill building show markers of both ore reduction and gold recovery processes. While outtake screens for the ball mill are absent (probably removed during the mill's final cleanup), grinding left a signature in particle size. More than 90 percent by weight of table concentrates passed through an 80-mesh sieve, and this suggests that the modifications to grinding size made by the Yellow Band Gold Mines were still in place when Fretzs took over operations in the 1950s.⁵² Like the analysis of ore samples, ICP-AES detected only limited quantities of gold in milling sediments. The highest levels came from the table concentrate bin where gold carried a value of between 4 and 8 ppm (a paltry $3.5 to $7 per ton in Depression-era prices). Whereas samples taken from ore deposits and mine overburden piles contained no detectable mercury, elemental analysis identified elevated levels in the ball mill feeder (39 ppm) and even higher mercury concentrations (279 ppm) in the table concentrate bin. The physical inspection of table concentrates, conducted in 1996, also identified the presence of free gold, native mercury, and mercury-gold amalgam.⁵³ These findings clearly corroborate the existence of amalgamation in the mill's recovery circuit. They also suggest that Baldwin's practice of redirecting concentrates back to the ball mill not only increased the odds of capturing additional free gold but also made savings by recycling unused mercury and affording the plates another opportunity to catch already-formed amalgam. In this sense, the ball mill technically upstaged the amalgamator as the first site of gold recovery.⁵⁴

Trends in element concentrations across the different mill bins also document the workings of gravity concentration (figure 10). XRF results indicate that elements with an atomic mass of greater than 50 (arsenic, iron, and lead) increased in concentration as they passed from the feeder to the classifier and table concentrate bins, while lighter elements (aluminum, calcium, potassium, magnesium, and sodium) showed the opposite trend. The notable exception, sulfur (atomic mass 32), possibly follows the pattern of heavier elements because of its association with metallic sulfides such as arsenopyrite, chalcopyrite, pyrite, sphalerite, and galena, known to be prevalent in the district's ores. Similar reasoning probably explains more erratic patterns in concentration found among elements representing less than 0.1 percent of the sample weight—namely that an element's separation into either saved concentrate or tailings followed the character of dominant elements in a compound.

Tailings

Elemental analysis encountered some difficulties in determining gold concentrations in tailings samples. Initial tests of 2001 samples by XRF indicated comparatively high gold levels (70 ppm), but subsequent analyses calculated dramatically lower values. ICP-AES analysis of these samples using nitric-acid digestion reported gold below 8 ppm, the lower detection limit of this method. Subsequent examination by ICP-AES total digestion, a method involving less dilution of the sample and capable of detecting gold as low as 0.1 ppm, recorded concentrations at 0.2 ppm (a loss of 14 cents per ton). While XRF results likely represent a concen-tration miscalculation caused by interference with other elements, the continued closeness of gold concentrations to instrument detection limits together with the recognized mobility of gold in leaching tests also caution against interpreting ICP-AES concentrations as inferring a higher milling efficiency than historically reported.⁵⁵

Figure 10. XRF analysis of sediment samples collected from bins inside the Lucky Girl mill. Chart shows concentrations of elements representing 0.1 percent or greater sample weight, with the exception of the dominant mineral, silica (not depicted).

Elemental analysis had better success in recognizing gold recovery techniques. Little could be made of gravity concentration processes because most element concentrations (gold and copper, the exceptions) registered higher in tailings samples than in mill heads. Amalgamation, however, left its characteristic imprint. Mercury concentrations in the Lucky Girl mill tailings varied from 1 to 170 ppm (figure 11), the highest levels significantly greater than the 3 to 38 ppm reportedly lost on average when working free-gold ores.⁵⁶ Leaching seems an unlikely explanation for higher values since 1996 and 2001 samples derived from the upper surface of the tailings deposit and because the highest mercury concentrations came from the sample site closest to the mill building. Instead, mercury levels are more likely to represent values diminished from historic concentrations. Mercury wastage may have been induced by the presence of arsenopyrites in the Sheriff ores. Significantly, mining engineers considered arsenic a leading cause of mercury loss in amalgamation and, at Bremner, tailings samples with the highest mercury concentrations are also those with the highest arsenic levels.⁵⁷

Figure 11. The elemental composition of Lucky Girl mill tailings taken from different sample locations (see figure 9). Concentrations attained by 40-element ICP-AES total digestion, with mercury tested by Cold Vapor AAS. To aid comparison with data collected from milling sediments (figure 10), 10,000 ppm is equivalent to 1 percent sample weight.

While a firm connection between tailings samples and a particular ore source cannot be established, tailings samples most likely pertain to the milling campaigns of the Yellow Band Gold Mines or from Fretzs's cleanup work. First, all samples came from the surface or near the surface of the waste pile, and although these samples are from altered deposits, the slide probably did not impact earlier mill runs buried deeper in the deposit. That more than 90 percent of tailings samples passed through an 80-mesh sieve also suggests, but does not itself prove, a post-1938 date.⁵⁸ The elemental profiles of tailings and mill bin ores parallel each other in a general way—where an element concentration is relatively high in the ore sample, it also tends to be relatively high in the tailings (figure 11). Notably, all ore samples follow this general trend with the tailings.

Tailings samples share generally similar profiles, but some differences in element concentrations are notable. Arsenic, lead, and mercury have the greatest spread of values, with concentrations varying by two orders of magnitude (figure 11). Tailings samples also tend to be "bunched" by collection period, and those collected in the 2001 season generally have lower concentrations than those sampled in 1996. Curiously, in comparing the two samples taken in 2001, some elements with known susceptibility to leaching (for example, arsenic, iron, and mercury) show higher concentrations in the upper layer. Without an extensive sampling program, however, a single explanation for these differences cannot be forwarded. Large variations in element concentrations may be a consequence of differential leaching processes, historical differences within or between ores, changes in milling techniques, or a combination of these factors. Smaller elemental variations could indicate historically significant differences as well, but, given overlapping margins of error, these could also be the creations of testing instruments and sample selection methods.

Discussion and Conclusion

Chemical analysis indicates that mining and milling deposits retain a range of historical information. Ore samples taken from the mill resemble those from a particular mine; recovery processes such as amalgamation (and gravity concentration to a lesser degree) leave traces in the elemental composition of milling sediments; ore reduction stages leave signatures in particle size. More tentatively, milling wastes also furnish some qualitative indicators of operative efficiency, particularly with regard to mercury loss. All told, if results from Bremner represent the most detailed information ascertainable from abandoned mining wastes, then the outlook for future archaeological studies holds promise, albeit with qualifications. Realistically, researchers could glean much of this information from written records and site surveys, without the need for extensive laboratory analysis. Indeed, the numerous caveats for interpreting historical conditions from present-day chemical signatures—such as the need to account for post-depositional processes, sample size and representativeness, laboratory procedures, and instrument errors and detection limits—can be anticipated to factor into all mine waste studies. It is sobering, too, that the wastes sampled at Bremner were relatively simple deposits, formed without the use of size-separating devices certain to complicate site stratigraphy and the ability to "reconstruct" wastes ejected from the mill. These techniques were commonly implemented at larger mines, the sites most subject to environmental remediation.

Substantial limitations exist, then, in using environmental characterization studies to also serve the purposes of historical inquiry. Arguably, however, some restrictions could be overcome (or at least better controlled) if incorporated early into the design of waste characterization programs. Data taken primarily from the upper levels of waste deposits (as at Bremner) or strategies that mix different sampling locations to form an overall composite (another common technique) mask the internal variability of deposits. Sampling from vertical profiles would enable researchers to observe leaching and oxidation processes in greater detail and potentially enable the assessment of changes over time. An analytical strength of this approach is that it provides a firmer basis for interpreting whether element concentrations are the likely consequence of leaching and oxidation processes or whether the variation is due to other factors. Historical interpretations would benefit also from combining qualitative and quantitative approaches, analyzing mineral phases together with an assessment of concentration ranges for a given element. Other analytical techniques may also be of service. For cases where valued metals such as gold are identifiable in waste materials in sizable amounts, optical microscopy might usefully distinguish gold not recovered from gold not recoverable by milling techniques.

As this suggests, archaeologists and historians need not pursue these lines of inquiry independently of environmental research. Indeed, environmental characterization programs remain imperative to historical studies of wastes because they determine the susceptibility of specific deposits to acid generation and leaching. Moreover, environmental testing programs show signs of increasing compatibility with archaeological methodologies. Recent procedures for characterizing mine wastes, for instance, stress three-dimensional sampling to better account for the internal heterogeneity of deposits, one environmental testing handbook noting, "If a tailings pile has several levels, each level represents a different time period and must be sampled separately."⁵⁹ Lastly, and arguably most critically, environmental researchers will continue to examine historic and abandoned mining wastes in the foreseeable future—and archaeologists and historians ought to be involved in this process.

Acknowledgements

Anne Worthington, Patrick Martin, and Richard Gould provided support and suggestions during various phases of this project. Survey work and documentary research of the Bremner Historic District was conducted in 1997 and 1998, with funding provided by a cooperative agreement between Michigan Technological University and Wrangell-St. Elias National Park and Preserve, Alaska (WRST). During the course of this research, Sylvia Baldwin graciously lent me company documents and photographs of her father's activities in the Bremner District—materials that now reside in the Asa C. Bald-win collection at the Alaska State Library, Juneau. The Brown University Anthropology Department and WRST funded archaeological investigations in 2001, and I was aided in the field by WRST seasonal archaeologists Kory Cooper and Susan Sura. At Brown University, David Murray and David Drew generously performed XRF and ICP-AES analysis using MacMillian Hall Environmental Chemistry facilities. I am grateful to Fred Quivik for bringing my attention to the Handy article (n. 9) and extend thanks to David Murray, Mal-colm White, Ed Hathaway (EPA), Bill Lovely (EPA), Terry Reynolds, Andrew Huebner, and Siân Silyn Roberts for comments on the final draft.

Notes

^1. Roper Research on the public favorability of industries, 1992 and 1994, cited in Sharon Prager, "Changing North America's Mind-Set about Mining," Engineering and Mining Journal 198, no. 2 (1997): 36–44.

^2. Robert L. Hoye and S. Jackson Hubbard, "Mining Wastes" in Standard Handbook of Hazardous Waste Treatment and Disposal, ed. Harry M. Freeman (New York: McGraw-Hill, 1989), sec. 4, 48–49; gold ring estimates derive from the Mineral Policy Center, a nonprofit organization dedicated to reducing the destructive impacts of mines on communities and the environment.

^3. Hoye and Hubbard, "Mining Wastes," sec. 4, 49 (see n. 2).

^4. George A. Teague, "The Archaeology of Industry in North Amer-ica" (PhD diss., Univ. of Arizona, Tucson, 1987), 205.

^5. See, for instance, Hans-Gert Bachmann, The Identification of Slags from Archaeological Sites, Institute of Archaeology, Occasional Publication 6 (London: Institute of Archaeology, 1982); Jerzy Piaskowski, "Distinguishing between Directly and Indirectly Smelted Iron and Steel," Archaeomaterials 6 (1992): 169–73; W. Rostoker and James Dvorak, "Wrought Irons: Distinguishing between Processes," Archaeomaterials 4 (1990): 153–66; Robert B. Gordon, "Material Evidence of Ironmaking Techniques," IA: Journal of the Society for Industrial Archeology 21, no. 2 (1995): 67–80, and "Process Deduced from Ironmaking Wastes and Artifacts," Journal of Archaeological Science 24 (1997): 9–18; Robert B. Gordon and David Killick, "The Metallurgy of the American Bloomery Process," Archaeomaterials 6 (1992): 141–67; David Landon, Patrick Martin, Andrew Sewell, Paul White, Timothy Tumberg, and Jason Menard, "'... A Monument to Misguided Enterprise': The Carp River Bloomery Iron Forge," IA: Journal of the Society for Industrial Archeology 27, no. 2 (2001): 5–22.

^6. For an excellent account of the mining industry's changing disposal practices and their environmental consequences, refer to Duane A. Smith, Mining America: The Industry and the Environment, 1800–1980 (Lawrence: Univ. Press of Kansas, 1987).

^7. F. E. Marcy, "The Enrichment and Segregation of Mill Tailings for Future Treatment," Transactions of the American Institute for Mining Engineers 58 (1917): 178.

^8. Arthur F. Taggart, Handbook of Ore Dressing (New York: John Wiley and Sons, 1927), 1284.

^9. Marcy, "Enrichment and Segregation," 178–83 (see n. 7); Otto Ruhl, "Mine Tailings, the Basis for a Growing Industry," Mining and Engineering World 35, no. 16 (1911): 733–35; R. S. Handy, "Treatment of Tailing and Ore in the Sweeny Mill," Mining and Scientific Press 30 (August 1919): 289–94; "Tailings Disposal Innovations," Engineering and Mining Journal 131, no. 6 (1931): 275; John B. Huttl, "Re-Treating Complex Tailings at Ophir, Utah," Engineering and Mining Journal 141, no. 5 (1940): 52–53; Taggart, Handbook, 1287–88 (see n. 8).

^10. Robert S. Lewis, "Milling Calculations," Chemical and Metallurgical Engineering 20, no. 5 (1919): 224–33; A. L. Engel, "Some Aspects of Ore-Dressing: General Observations on the Conduct of Daily Operations in the Plant, Made from the Viewpoint of an Operating Engineer," Mining and Metallurgy 12, no. 298 (1931): 447–49. The regular testing of mill sediments seems to have been a late-19th-century development. Arthur Taggart notes, for instance, that for the typical mill in the 1870s, "Head assays were substantially unknown. Feed tonnage was 'guesstimated' ... Moistures were agreed upon, often in the Russian sense. Tailings were similarly manhandled." Taggart, "Seventy-Five Years of Progress in Ore Dressing" in Seventy-Five Years of Progress in the Mineral Industry, ed. A. B. Parsons (New York: American Institute of Mining and Metallurgical Engineers, 1947), 118.

^11. Robert H. Richards and Charles E. Locke, Textbook of Ore Dressing, 3rd ed. (New York: McGraw-Hill, 1940), 355. There are copious examples of milling modifications, but for a sense of some different possibilities, refer to tables in Charles F. Jackson and J. H. Hedges's "Metal Mining Practice," U.S. Bureau of Mines Bulletin 419 (Washington, DC: GPO, 1939), 404, 406–19, which detail the circuits of 28 gold mills.

^12. Handy, "Treatment of Tailing," 289 (see n. 9).

^13. See, for instance, Robert G. Eppinger, Paul H. Briggs, Danny Rosenkrans, and Vannesa Ballestrazze, "Environmental Geochemical Studies of Selected Mineral Deposits in Wrangell-St. Elias National Park and Preserve, Alaska," U.S. Geological Survey Professional Paper 1619 (Washington, DC: GPO, 1999), 34.

^14. Roger P. Ashley and Charles N. Alpers, "How Mineral Deposits Interact with the Environment," Abandoned Mine Lands Preliminary Assessment Handbook, State of California, Environmental Protection Agency, Department of Toxic Substances Control (State of California, 1998), Appendix B, 1–2; Robert B. Vaughn, Mark R. Stanton, and Robert J. Horton, "A Year in the Life of a Mine Dump: A Diachronic Case Study" in Tailings and Mine Waste '99 (Rotterdam: A. A. Balkema, 1999), 475–84.

^15. Michael Trinkley, "Archaeological Investigations at the Reed Gold Mine Engine Mill House (31CA18**1): Reed Gold Mine State Historic Site, Cabarrus County, North Carolina," Chicora Foundation Research Series 6 (Columbia, S.C.: Chicora Foundation, 1986), 28, 40, and "Additional Investigations at the Reed Gold Mine Engine Mill House, Reed Gold Mine State Historic Site, Cabarrus County, North Carolina, 31CA18**1," Chicora Foundation Research Series 12 (Columbia, S.C.: Chicora Foundation, 1988); George A. Teague and Lynnette O. Shenk, "Excavations at Harmony Borax Works: Historical Archaeology at Death Valley National Monument," Western Archaeological Center, Publications in Anthropology 6 (Tucson: National Park Service, 1977), 172–77, 192.

^16. Charles V. Baltzer, "Developing Mineral Waste Sampling Plans for Reprocessing Studies," Hazardous Materials Control Research Institute, Monograph Series: Sampling and Monitoring 1 (Silver Spring, Md.: Hazardous Materials Control Research Institute, 1991), 104. Custom mills processed ores from different companies, with prices varying by tonnage, complexity of the operation, and stipulations for the final product.

^17. For an introduction to the legislative background of Superfund, refer to Richard Stanford and Edward C. Yang, "Summary of CERCLA Legislation and Regulations and the EPA Superfund Program" in Standard Handbook of Hazardous Waste Treatment, sec. 1, 29–45 (see n. 2). The EPA currently lists 88 mining sites on its National Priority List, with the total cost of cleanup estimated at $2.8 billion. EPA projects encompassing extensive mining regions include the Bunker Hill Mining and Metallurgical Complex, and Stibnite/Yellow Pine Mining Area in Idaho, the Oronogo-Duenweg Mining Belt, Missouri, and, in Montana, the Basin Mining Area, Barker-Hughesville Mining District, Upper Tenmile Creek Mining Area, and Carpenter Snow Creek Mining District. USEPA, Abandoned Mine Lands Team, Reference Notebook (Sept. 2004) <http://www.epa.gov/superfund/programs/aml/tech/amlref.pdf>.

^18. U.S. Bureau of Land Management, Abandoned Mine Lands Task-force, Abandoned Mine Land Inventory and Remediation: A Status Report to the Director (1996); see also U.S. Geological Survey, "The USGS Abandoned Mine Lands Initiative: Protecting and Restoring the Environment near Abandoned Mine Lands," U.S. Geological Survey Fact Sheet 095–99 (Reston, Va.: U.S. Geological Survey, 1999).

^19. Bill to Provide for the Reclamation of Abandoned Hardrock Mines and for Other Purposes, HR 504, 108th Cong., 1st sess., Congres-sional Record, 149, (29 January 2003): H244. [HR 504 is currently awaiting executive comment from the Department of the Interior.]

^20. Donald L. Hardesty, "Issues in Preserving Toxic Wastes as Heritage Sites," The Public Historian 23, no. 2 (2001): 19–28; Fredric L. Quivik, "Integrating the Preservation of Cultural Resources with Remediation of Hazardous Materials: An Assessment of Super-fund's Record," The Public Historian 23, no. 2 (2001): 47–61.

^21. For examples of the landscape approach, see Richard V. Francav-iglia, Hard Places: Reading the Landscape of America's Historic Mining Districts (Iowa City: Univ. of Iowa Press, 1991); Donald L. Hardesty and Barbara J. Little, Assessing Site Significance: A Guide for Archaeologists and Historians (Walnut Creek, Calif.: Altamira Press, 2000); Bruce R. Noble and Robert Spude, "Identifying, Evaluating, and Registering Historic Mining Sites," National Register Bulletin 42, revised ed., National Park Service, Intera-gency Resources Division, National Register of Historic Places, 1997.

^22. A troy ounce is 1/12 of a pound (compared to the usual 1/16) and was used regularly in the assaying of precious metals.

^23. See Ernest Patty, "The Airplane's Aid to Alaskan Mining," Mining and Metallurgy 18, no. 362 (1937): 92–94. For a general history of mining in the Copper Basin, refer to William Hunt, Mountain Wilderness: Historical Resource Study for the Wrangell-St. Elias National Park and Preserve (Anchorage: National Park Service, 1991).

^24. Indicating the improved conditions for precious-metal mining, the number of mines producing gold and silver in the United States rose from approximately 1,200 placer and 2,000 lode operations in 1929 to, respectively, 7,400 and 4,650 in 1935, with gold production rising from 689,403 fine ounces to 3,222,116 fine ounces. J. P. Dunlop, "Gold and Silver" in Minerals Yearbook 1930 (Washing-ton, DC: GPO, 1933), 817, 827, and "Gold and Silver" in Statisti-cal Appendix to Minerals Yearbook 1935 (Washington, DC: GPO, 1936), 337; Chas. W. Henderson and J. P. Dunlop, "Gold and Silver" in Minerals Yearbook 1936 (Washington, DC: GPO, 1936), 92. See also Charles W. Miller, The Automobile Gold Rushes and Depression Era Mining (Moscow: Univ. of Idaho Press, 1998).

^25. J. C. Roehm, "Preliminary Report of the Bremner Mining Company, Hanagita-Bremner Mining District," Alaska Territorial Department of Mines Property Examination 87–3 (1936), Bureau of Land Management, Alaska Resources Library, Anchorage, PE 87–3.

^26. Higher metal prices and the ability to reduce gold ore to bullion cheaply were likely factors behind a noted trend that gold-mining operations tended to construct milling plants earlier in mine development than the mining of base metals. E. D. Gardner and C. H. Johnson, "Mining and Milling Practices at Small Gold Mines," U.S. Bureau of Mines Information Circular 6800 (Washington, DC: GPO, 1934), 4. The cost of milling equipment at the Lucky Girl mill is provided in "Yellow Band Gold Mines, Inc. Balance Sheet, 31 December 1939," MS 36–1–10–8, Asa C. Baldwin Papers, c. 1907–1942, Alaska State Library, Juneau (hereafter cited as Bald-win Papers).

^27. A number of gold-recovery methods more efficient than amalga-mation and gravity concentration were in existence by the 1930s. Flotation and cyanidation, for instance, were both capable of working poorer, more refractory ores. Amalgamation and gravity concentration methods nevertheless remained popular among small-scale operators for several reasons. For one, small-scale mines tended to work less-complex deposits, to which these techniques were best suited. These methods were also comparatively cheaper, required fewer man-hours to operate, and could be run by less-skilled operators—of particular benefit to smaller operations where labor resources were often limited. Refer to Gardner and Johnson, "Mining and Milling," 19–28 (see n. 26).

^28. The arrangement of the milling circuit derives from field observations and a detailed description in Roehm, "Preliminary Report," 4 (see n. 25).

^29. J. C. Roehm, "Investigations: McCarthy, Nizina River, Bremner and Chisana Mining Districts: Summary Report and Itinerary of J. C. Roehm," Alaska Territorial Department of Mines Itinerary Report 195–14, p. 8 (1936) Bureau of Land Management, Alaska Resources Library, Anchorage.

^30. Fred Moffit, "The Lower Copper River Basin, Alaska: The Taral and Bremner Districts, The Chitina District," U.S. Geological Survey Bulletin 520-C (Washington, DC: GPO, 1912), 10, and "Geology of the Hanagita-Bremner Region, Alaska," U.S. Geological Survey Bulletin 576 (Washington, DC: GPO, 1914).

^31. Asa Baldwin, "Yellow Band Gold Prospect, Golconda Creek, Bremner District, Alaska" (1935), and "To the Unitholders [sic] in Yellow Band Gold Option," MS 36–1–10, items 1 and 3, Baldwin Papers, 10 March 1937, p. 2; Fred Moffit, "Recent Mineral Developments in the Copper River Region," U.S. Geological Survey Bulletin 880-B (Washington, DC: GPO, 1937).

^32. The Sheriff claims were formerly known as the "Nelson Prospect," but the name evidently changed upon its acquisition by Yellow Band Gold Mines. Asa Baldwin, "Notice of Special Meeting of Stockholders" (1938), and "Yellow Band Gold Mines, Inc. President's First Annual Report to Stockholders" (1938), MS 36–1–10, items 4 and 5, Baldwin Papers.

^33. Asa Baldwin, "Journal of the Yellow Band Gold Mine, 1940–41," entry 4 July 1941, MS 36–1–2–4, Baldwin Papers.

^34. Baldwin, "Yellow Band," (see n. 32); Asa Baldwin, "Annual Report 1939" and "Annual Report 1940," MS 36–1–10, items 7 and 9, Baldwin Papers.

^35. The contract for Yellow Band, rewritten just prior to the purchase of the Bremner Gold Mining Company holdings, allowed the Baldwin to pay royalties of 25 percent to the original claim-holders for any ore from the Yellow Band taken to the mill, with a minimum cash payment of $1,500. Baldwin, "Yellow Band," 2, 6 (see n. 32).

^36. Asa Baldwin, "Assay Map, Sheriff Claims, Yellow Band Gold Mines, Inc., Golconda Creek, Alaska," MS 36–1–8–28, Baldwin Papers.

^37. Baldwin, "Annual Report 1939," 4 (see n. 34); Baldwin, "Journal," entry 4 October 1941 (see n. 33).

^38. Baldwin, "Journal," entry 23 July 1941 (see n. 33). The Bremner Gold Mining Company may also have suffered a similar problem with the concentration circuit, mine inspector J. C. Roehm noting, "Very little concentrate is collected on the [Wilfley] table since most of the mineralization is oxidized and passes off in the tails." Roehm, "Preliminary Report" (see n. 25).

^39. Asa Baldwin, "Annual Report 1941," 3–4, MS 36–1–10–11, Baldwin Papers; also "Journal," entries 30 April to 1 June 1941 (n. 33).

^40. C. E. Needham, "Gold and Silver," Minerals Yearbook 1942 (Washington, DC: GPO, 1944), 80–81.

^41. Claude Stewart to Mrs. Asa C. Baldwin, 10 November 1946, 15 March 1948; and Paul Fretzs to C. F. Taplin Jr., 9 January 1960, MS 36–1–11, items 13, 16, 18, Baldwin Papers.

^42. Paul Fretzs to Sylvia (Baldwin) Johnson, 26 March 1975, 17 April 1978, MS 36–1–11, items 22 and 24, Baldwin Papers.

^43. For a complete description of sample methodology, sample size, and analytical techniques, refer to Robert G. Eppinger, Paul H. Briggs, Danny Rosenkrans, Vannesa Ballestrazze, José Aldir, Z. A. Brown, J. G. Crock, W. M. d'Angelo, M. W. Doughten, D. L. Fey, P. L. Hageman, R. T. Hopkins, R. J. Knight, M. J. Malcolm, J. B. McHugh, A. L. Meier, J. M. Motooka, R. M. O'Leary, B. H. Roushey, S. J. Sutley, P. M. Theodorakos, and S. A. Wilson, "Geochemical Data for Environmental Studies of Mineral Deposits at Nabesna, Kennecott, Orange Hill, Bond Creek, Bremner, and Gold Hill, Wrangell-St. Elias National Park and Preserve, Alaska," U.S. Geological Survey Open-File Report 99–342 (Washington, DC: GPO, 1999); Eppinger et al., "Environmental Geochemical" (see n. 13).

^44. For testing methodology, refer to Eppinger et al., "Geochemical Data," 8–9 ( n. 43).

^45. These techniques come with different methods. Laboratory analysis employed ICP-AES using total digestion and 10-element partial extraction, and trace- and major-element scan methods, cold-vapor AAS for mercury, and graphite-furnace AAS for determining gold concentrations. For a fuller description of these techniques and other analytical techniques employed, see Eppinger et al., "Geochemical Data," 10–13 (n. 43).

^46. Geochemical studies at other sites indicate that leachate tests do approximate the initial waters flowing from waste piles prior to their dilution by adjacent streams. Eppinger et al., "Environmental Geochemical," 34 (see n. 13). For a detailed description of the leaching methodology employed, refer to Eppinger et al., "Geochemical Data," 10 (n. 43).

^47. Eppinger et al., "Environmental Geochemical," 15 (see n. 13).

^48. The preservation of milling equipment and mill floors indicates that it is unlikely that these boulders derived solely from slide debris but probably resulted from the blasting necessary during the mill's construction (c. 1934). In all probability, a second launder dumped tailings southeast of the mill foundation—an area still covered with slide debris.

^49. SGS Minerals Services, Toronto (the same lab contracted to analyze USGS samples collected in 1996), performed 40-element ICP-AES total digestion and cold-vapor AAS for tailings samples collected in 2001. Tailings and other samples from the 2001 season were also analyzed using MacMillian Hall Environmental Chemistry facilities at Brown University. Here, ICP-AES analysis was performed on a JY2000 Ultrace ICP Atomic Emission Spectrometer, and XRF on a Philips PW 1480 wavelength dispersive sequential diffractometer, controlled by Phillips X40 4i software, and with data reduction by UniQuant 5 software.

^50. Roehm, "Preliminary Report," 7 (see n. 25); Moffit, "Lower Copper River," 10–11 (see n. 30).

^51. Eppinger et al., "Geochemical Data," CD Rom data files; Rock Samples, sample field nos. 6BR002R, 6BR003R1, 6BR010R, 6BR012R, 6BR014R1 (see n. 43).

^52. Percentage based on dry sample weight.

^53. Eppinger et al., "Geochemical Data," CD Rom data files; Heavy Mineral Concentrate, sample field no. 6BR002C2 (see n. 43). Significant gold (100 ppm) was found in the concentrates using an alternative sampling methodology, in which a large sample (approximately 16 pounds) was hand panned, sieved, and further concentrated to leave only heavy nonmetallic concentrates. By boosting gold values, this qualitative technique may facilitate the identification of some metal phases under microscopic techniques.

^54. Some operators chose to introduce mercury into the ball mill under the rubric that it was best to extract gold as early in the cir-cuit as possible. The downside of this practice was that, unlike stamp batteries, cleaning out the ball mill was an involved process, and it also increased the danger of mercury loss by "flouring" (refer to Gardner and Johnson, "Mining and Milling," 22 [n. 26]). According to diary entries, Baldwin recovered 1/2-ounce worth of amalgam "pellets" from under the ball mill liners in the 1941 season ("Journal," entry 10 October 1941) and gold recovery from the ball mill is suggested also in the previous year ("Journal," entries 15–18 October 1940) (see n. 33). That both cleanups occurred at the end of the milling season and recovered only a small amount of amalgam suggests that mercury in the ball mill came only from the reintroduction of table concentrates.

^55. As an element approaches minimum detection limits, the signatures of other elements in the sample can cause instruments to read higher values.

^56. Averages taken from Taggart, Handbook, 960 (see n. 8); Richards and Locke, Textbook, 65 (see n. 11); M. W. Von Bernewitz, Hand-book for Prospectors and Operators of Small Mines, 4th ed. (New York: McGraw-Hill, 1943), 395. Taggart directly states average losses in troy ounces per ton. The other estimates, which are higher, state only ounces per ton (for an explanation of troy ounces, see n. 22). In converting these numbers to ppm, I conservatively took all textbook estimates to be in troy ounces per ton.

^57. Arsenic induces the formation of a black film over the mercury, preventing it from alloying with gold. Charles F. Jackson and John B. Knaebel, "Gold Mining and Milling in the United States and Canada: Current Practices and Costs," U.S. Geological Survey Bulletin 363 (Washington, DC: GPO, 1932), 106.

^58. Particle size does not rule out the possibility that the Bremner Gold Mining Company also experimented with grinding sizes.

^59. State of California et al., Abandoned Mine Lands, Appendix D and E (see n. 14).

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