The Bald Mountain iMining Company and Cyanide Gold Recovery in the Black Hills

By Richmond L. Clow

T he Bald ;\fountain ;\fining Company was organized in 1928, three decades after the intro­duction of cyanide gold recovery pn1cticcs to South Dakota's Black Hills. Despite its late start, this company was the second largest gold pro­ducer in the Black Hills. What makes this feat so important was that the company mined and milled geologicall y complex, refractory, siliceous, low-grade gold ores that required the applica­tion of skillful practices to capture the precious metal. This made the company an important innovator of refractory milling practices, devel­

oping ideas borrowed from its predecessors and academic laboratory experiments.

The technological and economic importance of the Bald ;\fountain Mining Company to tl1e northern Black Hi lls begrtn decades before the company itself was organized. _-\t the turn of

the twentieth century, the precursors to the Bald ;\ fou ntain Mining Company, the ;\ fogul and the Gold Reward, replaced their stamping and cyii­nide decantation methods with Ch ilean mills and processed slimes by tJ1e i\ [oore process. 1

Nor were either tl1e region's or company's met­allurgical efforts unique in their attempts to re­cover metals from difficult ores. ;\[iners through­out _-\merica's western camps discovered depos­its of " rebellious" gold ores, so named because they refused to release metallic values except when treated with complex, often expens ive, reco,rery 1·echnologies. Californians encountered

sulphurets in quartz ore; ColonKio miners con­fronted tellurides; Black Hills operators wrestled Cambrian siliceous ore, locally called refractory ore.

i\ [etallurgical skills and processes were re­quired to capture gold in paying quantities from each of these ores. Some mining operations were fortunate. Instead of fighting their refractory ores, Homestake and other early companies worked the "fossil place deposits in the basal conglomerates of the D eadwood formation ." The ore from tJ1ese format ions was free-milling, its gold recovered by the time-proven California amalgamation process. 2

The situation changed in 1877, when .-\. J. Smith discovered the Bald i\ [ountain ores.3 Un­

like the large companies working the region's free-mi lling ore, a number of small mining com­panies staked claims to the Bald i\fountain mines west of Lead. But these small companies had a difficu lt time raising capital to conduct expen­sive experiments on refractory ores. :\ s a result, the Bald i\ [ountain Mining Company's nine­teenth-century predecessors began as small op­erations that were frequently reorgilnized and con­sol idated, a circumstance probably "more one of necessity than design clue to the problems con­nected with mining and treatment of the highly rcfractoqr siliceous orcs bodies, problems beyond the scope and capabilities of small, individual opera tors."4

Th is difficulty in capturing the gold \Vas even more troubling when siliceous refractory red oxi­dized and blue unoxidized ores were found o n the surface of the limestone from the ne~rby Ragged Top District "averag[ing] S100 per ton in car-load lots." Even tests on richer $200-a­ton ore produced only $10 in gold per ton.5 With such high values waiting to be taken, the refrac-

-J.8 2006 i'di llillg H iJ"fOI)' ] 0111'1/ai

to ry ore puzzle had to b e solved. The Bald Mountain ~lining District was lo­

cated near the base o f Terry Peak. The district

was two miles by five miles, lay southwest of th e Lead-Deadwood (-.f ining District, and was locally known by its subdivisions, named after the Ruby Basin, Porthmcl, and Trojan mines. :\lost of these Bald "\fountain deposits had a general

value o f three to five dlo llars per to n and the varied na ture o f the o res included quartz ledge replacem ent deposits, siliceous tellurides, red ores, and blue o res.6

Over time, mining engineers learned that the district's complex o re stniCture and mineral iz~t ­

tio n was created " by Tertiary igneous intrusions into the Precan1brian and Paleozo ic sequences. This is silver-rich and co ntains the usual types o f mineral assemblages, :such as tellurides." The early major companies wo rking these depos its along Nevada, Fantail, St1ewert, 13ox E lder, Terry, and .-\nnic Creeks were the G o lden Reward, the H orseshoe, the L\ logul, a111d the Tro jan. The last and mos t important o p eratio n was the Bald L\(ountain L\(ining Comp:any.7

Black H ills miners classified the refractory o res as eith er red o r blue:. The red o re was oxi­dized rock, ranging from several to a few hun­dred feet below the surface, that had been ex­posed to oxidizing activity Blue ore came from deep in a mine and included pyrites that had not been subjected to oxidatio n. N o distinct demar­cation separated the two ores, but as the depth

of a mine increased, mo re pockets o f blue ore were uncovered . Straig;ht cyanida tio n solved most o f the difficulties associated with recover­ing gold fro m red ore, capturing as much as 85 percent o f its gold. Blue: o re, however, did no t yield its wealth so readily.. Effective gold recov­ery from blue ore was further complica ted by its variable sulphur content, which would dicta te, to som e extent, effective recovery processes. Years of research would lbe deYoted to finding a pro fitable method of treating the Black Hills blue orcs found in the Bald ;:-..fountain ~fining Dis-

tric t.8

The first refractory-OJL"C experimen ts attempt­ing to recover gold fro rn both red and blue ores began in 1879 at the Empire ~line and contin­ued th e fo llowing year a t the Portland . These pro perties, a long w ith the Clinto n ~lin e, la ter becam e p ro perti es o f lthe co nsolida ted Bald .\fountain :\fining Company.9 Initially, the cos ts

of processing and experimenta tio n imposed upon th ese small companies that mined bo th red and blue ores required o re values o f $100 per ton. On the o ther hand, matte smelting and chlo ri­

mttion permitted lower-value refractory ores to be p rocessed.

Between 1883 and 1890, the Po rtland ;\ fin ­ing Company conducted many experiments o n

these difficult go ld o res. The company tried roasting the ore before stamp amalgamation, but only recovered 30 percent o f the gold. Later "bromine and cyan ide lixiviatio n were tried," and

failed, fo rcing the company to send low-grade o res to the D eadwood s.melter or to a custom cyanide mill a t Terry, probably the Lundberg, Dorr, and \\ 'ilson. By the beginning o f the twen­tie th cen tury, th e Portl and .\fine's rich Bald

.\fountain high-grade refractory o re deposits paid the cost o f out-of-s tate smelting.10

E xperiments were also co nducted o n \\lei­

come .\ [inc o re in 1883, and three years la ter more tes ts were conducted at the Buxto n ~line .

N one were success ful. During these early years o f failure, large quantities o f higher-grade blue

o re and blue-ore concentra te were shipped to outside smelters fo r fina l reduction. Local co m­panics continued to expe1riment on the blue and red o res, ho ping to discover a profitable treat­ment process. 11

In L\ lay 1887, the G o lden Reward ~fining Compan y was incorpo ra ted, bringing " th e G olden Reward, D ouble Standard, Little Bo­nanza, H armony, ~mel Stewart" mines under o ne company. The new compan y installed a barrel chlorina to r in 1889, and shortly thereafter the D eadwood and D ela\va re Sm elting Cornpany

Tbe Bald i\!Iomttain M.ining Compc"!Y 49

Trojan Mill e.Yleliorjrolll tbe JJ•ext, ,.. 1918-28, xbo1ring tbe xite JJ'tfb a!.! of i!J JlfjJjJOJ1-

ing buildil!'g,J. (1-liJ"torit· AI?ICiit·an Engineering Re,·ord, Librcny of Congrw)

completed a smelter. Each company's process recovered gold from bot11 blue and red ores, but at a high cost. Smelting costs r1mged from S-+.75 to $5.75 a ton, and chlor.ination costs from S3.50 to S-+.50 a ton. Only hiigh-grade refractory ore was sent to these plan ts .. 12

These matte smelting and chlorination prac­tices were successful, but too expensive when applied to low-grade refractory ores. Cyanidation was introduced into the Black Hills in 1893 in the hope of decreasing t·he cost of treating gold ore. This process was cheaper than either smelt­

ing or chlorination, costing as little as S 1.17 per ton at the Dakota cyanide mill in Deadwood.13

Early cyanide operations were simple. Ore was crushed and rolled to a thirty mesh, then leached in cyanide tank::; and precipitated with zinc shavings. The most important work on the process in the district was conducted at the Lundberg, Dorr, and Wilson custom cyanide mill at Terry. There John 'i/ N . Dorr developed a classifier to treat sands and slimes separately in 190-t, a continuous thiclkener for the slimes in 1905, and an agitator in 1907. These machines

made "continuous counter-current decantation cyanidation" possible, but more knowledge and technology were needed to treat the blue ore. 1~

Initially, the straight cyanide process was used on both red and blue ores. From the former it

recovered 70 to 85 percent of the gold contained, but from the h1tter it often yielded as li ttle as 35 percent, which was not enough to make a profit. C. G . \'\larnford Lock, an English mining engi­neer, and F. H. Bousfield, employed at the Black Hills Gold ~mel Silver Extraction ;:\[iningand :\fill­ing Company of Deadwood, conducted blue-ore

cyanidation experiments in 1895 . • -\fter achiev­

ing a recovery rate of less than -+8 percent, Lock concluded that cyanide would not treat blue ore raw. Consequently, most mining operators ig­nored these difficult unoxiclizecl deposits.15

The mining companies' disappointing experi­ments encouraged scientists to examine these ores. Frank Clemes Smith, on the faculty of the South Dakota School of :\fines, began experi­ments in the l890s, spurred by the economic im­portance of the Potsdam sandstone refractory ores to the northern Black Hills. He worked from

50 2006 1\llining Hist01y Journal

ThiJ 1942 ao.r.r-Jedion of the Bald i\!lo1111tain i\1ill illmtmteJ JJ'bere !be three mqjor promses of gold­ret'Ot-'e~y oamnd in the .flntdtrre and in relationJbip to ead; otbeJ: ComJe and jim t'rttJbing happened in the

upper Jedion of tbe Jtmdlfre. (yanide leadJing to e~\.lrad the gold took plaa in !be middle J"Cdion of the building. Gold J'Ct·ot·e,y from tbe cyanide Jollftion otmn-ed in tbe loJJ'erpart if tbe b11ilding.

(HistoJic Ame1imn Enginwing Ret'OJr!, Libra~y qf CongreJs.)

1/Je Bald 1\llolllltain 1\ifillillg CoJJ/pcii!J Sl

th e premise that tellurium-a sen1i-metallic ele­m ent related to selenium and sulfur that is a sil­

ver-white brittle cr ystalline form-often com­bined w ith other metals discO\'ered in th e Potsdam ores using red and blue samples from the \\feicom e i\Iine.

Having conducted his experiments, Smith eliminated amalgamatio n as a treatment method, but suppor ted smelting that lost the tellurium,

11nd the chlorination andl cyanide process, where tellurium might be saved. Based on the last two

reduction m etl10ds, roastingwas incorporated in several mill flow charts and set a pattern for fu­

ture experiments. \\falter P. Jenny commented o n Smith 's work, emphasizing thM this "district is well wortl1y of the attention of tl1c Institu te and should be brought to the attention of the United States Geologic:rd Survey, that the for­mation and pecul it~ r occurrences of these o re de­posits may be carefully worked out." 16

In 1907, B. D. O'Brien, another professor at the South Dakota School of i\fines, guided ex­

periments o n the blue 01re, hoping to discover a cost-effective treatment. Reporting on his work two years later, O'Brien concluded that blue ore, if finely ground, roasted, and then leached wit'11 potassium cyanide, would yield as much as 80 percent of its gold . Tie further surmised that use of bromocyanidc t~nd agitation and aeration during the treatm en t process could increase that yield to 90 percent. O'Brien's experimen ts in­

troduced extra procedures into the treatment process, but he believed that treatment of Black Hills blue ores by cyanidation alone would re­main ineffective, concluding that a " radical de­parture from present methods must be made if these ores are to be successfully trcatcd."17

~\fter these early School of i\fines experi­ments, a dect~de-long Black Hills cya nide boom ended in '1909, when labor troubles that began in 1906 finally shut down nearly every opera­tion. Homestake alone locked out twenty-five hundred workers. This labor unrest also closed d1e refractory mines at· Bald ;\fountain, and hin-

dered the region's mining companies from trying to implement any new metallurgical develop­ments to increase gold recovery rates from the

region's blue siliceous gold ores.18

~-\fter the labor troubles ended, millions of dollars waited ro be made from the low-grade refractory ores found in Bald i\fountain mines. The less-than-successful experiments did not stop investors from organizing the Trojan i\ fin­

ing Company, tJ1e forerunner to the Bald Moun­tain enterprise. The Trojan ;\ fining Company was founded in 1911, consolidating th e Portland, Clinton, ~-\merican Eagle, and other Bald 1\[oun­tain properties. 19 This "represented the consoli­

dt~tion of the old Portland i\Iining Company hold­ings with tl1c Clinton and ~-\merican Eagle prop­erties."20

;\ lost of the company's officers were from Chicago, but T-:T. S. Vincent was from Deadwood. Since many Black Hills mills and mines were idle, their deposits having been played out, the com­pany assumed con trol of the _ \merican E agle

i\ fill on Ft~lse Bottom Creek, a one-hundred-ton cyanide plant built in 1908.21 .After the Trojan Company obtained the _-\merican Eagle hi llside gravity mill, the company extensively remodeled the faci lity maki ng it

one of the best in tl1e Black Hills. Large concrete foundations, resting on solid rock, support the machinery and retain­

ing walls. T he superstructure is of wood, the fram e throughout being put t·ogether with mortise and tenon joints, secu red by wooden pegs. _-\. feature is the almost entire absence of iron bolts in tl1e frame. Splices arc rare, [and] only occur in unimportant parts of the frame. The frame is housed wit·h one-inch sheeting and the whole covered with

heavy rubberoid lJ"itJ building paper.22

This description of the Trojan i\fill, built on the _-\merican Eagle's structure, reveals the utili-

52 2006 Mi11i11g HiJtOJy ]ottn/(/1

tarian architecture employed in the region's gold mills, but also the fine craftsmanship employed in constn~et·ing them.

Initially, the Trojan was a dry-crushing cya­nide plant, with a twenty-four hour capacity of three hundred tons. The mill's unique structure of three ore bins permitted ores to be sorted into different bins. The ore bins emptied into a

crusher pit, where a No. 5 Gates crusher did the preliminary crushing in a cyanide solution . The ground ore was then moved by belt to two Eclipse rolls, where a strong cyanide solution-three pounds per ton-was added. Then the ore moved to one of two l\ [onadnock mills, and from there onto the Dorr duplex classifiers that sepa­rated sands from slimes. The sands were treated in launders, while the slimes went to a Dorr

thickener and then on to the final slime treat­ment, which was a stationary leaf filter. Slimes were ag-itated in Pachuca tanks. Zinc box pre­cipitation, using zinc shavings, was used to re­cover the gold from the pregnant solu tion. De­spite the state-of-the-art cyanide practice, blue ore recovery rates remained low, so high-grade ore was sent to a smelter in either Denver or Omaha.23

The o ngoing blue-ore puzzle provided both an economic and intellectual dilemma. _-\s a re­

sult, another series of experiments began after the Trojan i\fining Company commenced opera­tions. .-\nother researcher from the School of Mines, .-\mil .-\ . • -\nderson, class of 1913, pub­lished the results of his experiments on blue ore

several years after O'Brien's first experiments. _-\nderson selected o re samples from four mines-the Hardscrabble, Trojan, Bismarck, and Golden Reward-subjecting samples from each to thirteen separate recovery processes to assess their effectiveness. _-\nderson's conclusions, while not echoing O'Brien's results, were simi­lar. _-\nderson recommended crushing, roasting, and cyanidation as the primary elements of a suc­cessful treatment process for b lue ores.2·

1

C. G. \Villard, another student at the School

of ;\fines, conducted laboratory tests after _-\nderson's experiments. \'{Iillard, the future su­perintendent at the Golden Reward :\fining Com­pany, exposed the ore to temperatu re extremes by heating crushed ore to four hundred degrees centigrade before dropping it into cold water. The resulting rapid contraction of the ore caused

it to shatter, permitting subsequent cyanidation

of the ore to achieve a recovery rate of 91 per­cent.25

While laboratory experiments sometimes dem­onstrated that high blue-ore recovery rates were possible, those rates were not always realized when processes based on those experiments were implemented in the mill. The Golden Reward adopted a roasting treatment along the lines sug­gested by O'Brien's and _-\nderson's early work, and ini tiated the first large-scale commercial ef­

for t to process blue ore.26

In 1913, the company installed a Wedge me­chanical furnace at its _-\storia Shaft ;\ fine a few miles southwest of Lead. This furnace was ca­pable of roasting sixty-five tons of crushed ore in a twenty-four-hour period, gradually heating the ore to the preferred temperature by moving

it slowly through a series of progressively hotter levels. The ore was fed into the furnace's upper level near its outer circumference. Rabble blades, kn own as plows, attached to a shaft running ver­tically through the furnace continually raked the ore, moving it gradually (at eighteen to nine teen revo lutions per hour) toward the inner circum­ference of the hearth . Upon reaching the inner circumference, the heated ore dropped through holes in the hearth floor to the next level, where another set of rabble b lades slowly moved it to

the outer circumference, where it fell through drop holes to the next level. It took ore five hours to pass through the furnace.27

Furnace temperature increased as the ore fell

from one level to another, with the exception of the bottom level, which functioned as a cooling hearth. Between the top hearth on level seven

and the fire hearth on level two, temperatures

The Bald MoNntain Mini11g Colllpcll!)' 53

ranged from two hundred to twelYe hundred degrees Fahrenheit. \\~Her cooled the oil-burn­ing furnace. T he roaster consumed as much <lS

eleven gllllons of oil to roast one ton of hard blue ore, half that amount to treat a ton of soft blue ore. _-\ base-metal thermocouple-an elec­tric device that accura tely measured 1·empen1ture differences between dissimilar metals- con­trolled the temperature of the roaster.28

Temperature control was extremely imponant·

to the successful roasting of blue ore because proper roasting temperatures \·aried from batch to batch, depending upon the sulphur con tent of the ore being roasted. Soft blue ores were high in sulphur content, averaging ll percent o r more sulphur. Roasting soft o res required a maxi­mum temperature of eight hundred degrees Fahr­

enheit, while hard ores, low in sulphur, required twelve hundred degrees.29

Once roasted, ore was carried by rail to the Golden Reward cyanide mill in Deadwood, where hard blue ore was discharged into a weak cyanide solution and the gold extracted. Soft blue ore was first washed with water to remove cyanicides, the base metal residues that inhib­ited the cyanide gold recovery process from working properly.30 Golden Reward refractory

ores were not coarse bu t tightly compacted ores, and roasting was necessary to open the pyrites to expose the fine gold particles to a cyanide solu tio n.31

The roaster did not solve the problem of re­covering go ld from blue ore. Joseph P. Conno lly, professor of mineralogy, reported that the company's preliminary roasting still gave "very erratic results, and so far has not been commer­cially feasib le." The poor results discouraged mining companies, which mined o nly the oxi­dized red o re as a resul t. But by 1920, "most of the oxidized o re [had) been worked o ut," Connolly wrote, w hile "probably several n1illions of tons of blue ore still [remained] in the dis­trict." _-\ s mining companies depleted their reel­ore deposits, they began to close because the

available recoYery technology for blue ore was unprofitahle.32

Owners were unwilling to mine depos its worth only eigh t to ten dollars a ton to treat them with processes that recovered a relatively small percent11ge of their gold. "The proper solution o f the problem," Connolly concluded, "would thus add millions of dollars to the mineral re­sources of the northern Black Hill s." The

Golden Reward Company, for example, was thought to hm·e more than one-half million tons

of blue ore m·ailable for exploita6on when a com­mercially viable method of recovery was found:13

Based on the blue-ore milling and roast·ing e:--:periments at the School of :\[ines, the Troj;m :\ fi ning Company initiated its own experiments in 1915. The company enlarged the mill to in­

crease the capacity of its Dorr thickener and to provide more work room around the Chilean mills, a circular mill with center pi,·ot arms that

crushed ore against the mill's steel sides. \\"hen t·he ore was fine enough , it was discharged through screens on the sides. This mill improved the fine crushing of refracto ry ores. 3~ Then the company installed "a Holt-Dern roaster and the recovery was increased to ninety percent if the ores could be given a chloridizing roast.'' 35 From

these "exhaustive [on-site] tes ts it appcarlcciJ practically cert·ain that a preliminary roast lwould] make a large proportion of th e fbluel ores ame­mlble to cyanidation ." 36

The Trojan Company mined both red ;md blue ores, despite less-than-successfu l on-site recoY­ery rates fo r the more eli fficul t blue ores. _\s re­covery rates dropped, the Trojan Mining Com­pany treated fewer tons of ore. Despite reduced production, in 1919 th e company increased wages to SS per eight-hour shift for its under­ground workers and S-l-.50 for an eigh t-hour mill sh iftY ~[ining and treating low-grade blue ore with a low recovery rate forced the compilny to purchase additional properties in 1921, seeking

more profitable ore.38

The mill shut down in .\larch 1923, but· ex-

54 2006 i\1iJJil(~ I-liJto~y .Jolll'llal

plor~1tory work continued in the hope of finding

higher-gr11de refr<Jctory ore.39 General .\fanager C. E. Dawson stated: "Con tinued high cost has influenced us in reaching this decision . It has

been necessary to confine our mining operations 1·o a higher grade of ore than formerly, in order

to pay operating expenses. This has translated into a reduction in tonnage, with very little re­duction in costs." E,·en with the mill idle, the

con1pany completed se,·eral modifications to

make it a modern plant " in accordance with the best cyanide practice.""0

These early blue-ore experimen1·s did not lead to a key to unlocking the secrets of increasing

the regio n 's gold recovery rates from its unoxidized blue ore; when the Trojan mill closed,

it was merely another operation that fell victim to the refractory o re. Despite its lack of high­

gr~Jde refractory ore, Trojan ;\fining Company, with its low-gr,1de ore, was the district's second

highest producer of gold between 1918 and

1923, after T Tomes rake. High operating costs

~mel unprofitable go ld recovery rates from b lue ores idled the mine and mill in February 1923.~ 1

.-\fter the war, mill operating costs had risen and "gradually O\"ertook the margin of profit real­

ized from the low-grade [reel and blue] ores of the a rea with the 70% to 75% gold recoveries then possible."-12

The operators' problems with reducing local

low-gnde, refrt1Ctory gold ore did not end the Trojan's mining and milling efforts; instead it

was a lack of capital and credit. Based on past

operating success, the Lead and Deadwood branches of the r irst National Rank of the Black Hills loaned d1e company ~28,000. \Vith opera­

l·ions suspended during \\fo rl d \\/t1r T, the bor­rower lacked the funds necesst1ry to rept1y the

loan, making it impossib le for the company to

remain on a solid financial footing. TroJ~m's fi­nflncial problems continued to mount, as the

bank won a judgment against the loan, a debt

Bald Mo1111tai11 Mill e."\leJiorjroiJI tbe JJOJtbeaJt, ,.. 19-/.0-59. The roa.~ler a11d otber IIJJoxidezed ore dn:11it additiom are preJeJJt, afoJJg JJ•itb Je,·oJJdaD' thickeNer JJO. 7 aJJd additiOJJJ to tbe

IJiadJiJJe Jbop. (T-Tistori,· Anmit-cm EJJgiJJeeJiJJg Re,·ord, Ubra~y qf Co;lj!,re.f.r.}

Tbc Bald Ll1olflltaill Mi11i11g Compm!J' JJ

added to $20,000 in unpaid taxes and pre-exist­

ing labor liens.u T he search for more productive blue reduc­

tion prac1·ices continued despite the Trojan's

shutdown, as o ther rnine owners wmlted a bet­ter blue-ore reduction process so that they could reopen their id le mines. T he search fo r a solu­tion became more in tense in the early 1920s,

when Connolly, alo ng with gr~H.!uate students _-\rthur L Johnson ~md GeorgeS. ~\fcCracken, con­

ducted experiments on the blue ore's bonding properties at the South D~t kota School of ~fines.~4

They concluded that as much as 65 percent of the gold con t~tined in blue ore was bonded to

fine grains of pyrite, w hich, in turn, were bonded to the quartz. Since the qmtrtz prevented the cyanide solution from dissolv ing the gold, the

ore would have to be more finely ground for the cyanide process to work . Still, th is discoYery was only one step toward understanding the com­

position of the blue ore, 11nd it did no t completely soh·e the problem. Con noll y, Johnson, and

McCracken determined that fine grinding alone would not increase recoyery rMes to t1 profitable le\'el because most of the gold values were still

bonded to pyrite and quflrtz. 15

In '192-1-, several Black Hills mine owners re­

quested that the United States Bureau of Mines initiate new blue-ore experiments. These min­ers wanted the bureau to expand blue-ore stud­

ies beyond the work conducted at the School of J\fines. T he bureau agreed, first conducting small laboratory experimen ts, then constructing a one­ton demo nstration mil l at the South Dakota School of i\fines for larger trials . ~6

Bureau engineers worked from the premise

that arsenic, a cyanicide found in the blue ore, prevented dissolu tion of the gold in cyanide. Ore was firs t coarsely crushed, then subjected to a

short, low-temperature mast of sufficient heat and duration to prevent the arsenic from form­ing destructi,·e base compounds and to oxidize the pyrite in order for dissolution of gold to oc-

cur in the cyanide. Slaked lime (calcium hydrox­ide) in water was added to each ton of ore after

roasting. The lime created sufficient a lkalinity in the pulp to minimize the loss of cyanide in the subsequent treatment process. :\fter the lime

was added, the ore was ground fine and put through a "standard cyanide treatment."~-

Using this process on blue o re from the Tro­jan .\line, the Bureau of .\ [ines obtained reco,·­

ery rates of slightly O\'er 97 percent of gold, and 91 percent of s ilver. ~ 8 Connolly, from the School

of .\ fines, attempting to expand on the hure~tu's tests, reporting in I 927 that a "water quench ;1f­

ter roast at 800 ldegreesJ C g,we Yery good re­sults," but his results could no t be dupliettted. 19

D espite these promising bureau tests, a sec­ond cyan ide boom was not forthcoming. Eco­nomic conditions in the ·1 <J20s that included a

low price for gold <mel high s tart-up costs pre­vented operators from reopening id le refr<tctory mines. Despite these gloomy ci rcumstances, the

promising experiments gm·e one group of inves­tors the courage to reopen the Trojan properties

at Bald .\fountain.50 Previous production pro­vided some reason for optimism, as over S31 million in gold was reCO \'ered from Bald .\{oun­

tain mines from 1875 to 1933.

Bald M oun tain M ining District Gold Producf ion to 1933

Company Value Tonnage Golden Reward $2 1,000,000 3,570,000 (?) Mogul $4,750,000 807,500 ('!) Ann ie Creek £875,000 148,500 (?) Tr~1~a~~~ --------~$~, 5~.2~s~o~,o~o~o ____ ~8~9~2~.7~8~9 TOTAL $3 1,875,000 5,405,789

{Prom 1-f!fiJIIIIC/, "S frtrt'flfi'C a11r/ i\Jillem/i~pliOII, " p. 68.)

The Trojan mining properties and mill, idle

since I 923, begtm <t new life fi\·e years later when the Bald ;\[ountain ;\[ining Company was orga­

nized. There were several keys to financing this

new company. One Wits outside money, made possible by an improvement in the honesty of the local mining con1munity-th is after incidents

56 2006 Mi11i1{~ T-liJ'IOI)' foumal

like the Jlarney Peak tin Yenture, whe n one backer described Black Hills companies as run by " bunko steers, confidence men and horse thie,·es."51 The Lead and Deadwood branches of the First National Bank of the Black Hills

also provided good fimmcia l support The t~'irst National wanted t·o make good its

loan against the Trojan property and reopening it was the best way for the bank to rccoYer its money. So local bankers were instrumental in starting th e Bald :\fountain :\fining Compan y. Robert H. Driscol l and his son Robert E. Driscoll, and \V 1 ~ . . -\darns, the Lead and Dead­wood officers of the f'irst l'ational Bank "were willing t·o bet· any amount on a deal which in their judgment had n1eri t."52

Robert E . Driscoll eventually convinced a group from Clinton, Iowa, and Chicago to front the two hundred t·housand dollars necessary to free the Trojan company from its financi11l troubles so that operations could begin.53 Their on ly stipulation was th~1t "the bank would ride with them for part· ownership." The bank's of­ficers "agt:eecl on condition that the amount we had in labor liens and taxes be paid first and that

we be given preferred stock for our original debt and interests, together with $10,000 of common

st·ock for which we paid this amount."5·'

The new company, a consolidation of Tro­jan and ~fogu l holdings,5

" con trolled "the Trojan ;\lining Company, Imperia l ;\fining Company,

Two Johns ~fining Company, and part of the holdings of the ~fogul :\fining Company." 56 .-\II told, the new company owned 2;100 patented

acres and the remodeled Trojan m ill, five miles west of Lead, with which to begin their quest to

make a protlt from low-gt·ade blue and red re­fntctory ores.5- \\fhile th e Bald :\fountain prop­

erties began production, the Golden Reward re­mained closed and, in 19-+2, .-\naconda Copper ~fining Comp;my purchased the mine.

C. F. Dawson, general manager of the Tro­jan ;\lining Company, was hired to supervise the Bald i\ fountain ;\lin ing Comp;my's start up. He

began development work in 1928 and stopped two ye;1rs later. 58 Development consisted of driv­ing a 1,270-foot tunnel at a twenty-seven de­gree negative slope "from the bottom of the ·1 \vo Jo hns ;\fining Company, which had fau lted downward from t·he old Rua working-s on the rim

of the canyon ." 59

_-\s this exploratory work began, Bruce C. Yates, general manager of the Homestake ~ fin­

ing Company, hired consulti ng geologist Donald r f. .\lcLaughlin to report on the Bald ~\(ountain

mmcs. Ob,·iously, Yates was interested in the Bald ;\fountain mines as potential I-Iomestake properties. ;\IcLaughlin reported that the first·

Gold Reward di11moncl drill hole produced poor results. On the positive side, the Tornado Shaft had blue ore that averaged five dollars per ton, and low-grade brown ore was distributed every­where.

Overall, ;\ fcLaughlin did not see an optimis­

tic future for the Bald Mountain mines. The low­grade ore might produce a profit, but he con­cluded that the " reward, howe\'er, can not be considered particularly attractive in view of the effor t that would be needed to make the enter­prise a success."60 McLaughlin's pessimistic re­

port steered Homestake away from purchasing any interest in the Bald ;\fountain Mining Com­pantcs.

In 1933 the price of gold rose,61 and tJ1e Bald

;\fountain ;\fining Company reopened its mines, taking bod1 red and blue ores. The company was the on l)' major gold-mining operatio n besides the Homestake to initiate both underground mining and surface reduction operations in the Black Hills. In January 193-J., the mill was operating again.62 The govern ment-sponsored increase in

the price of gold "from S20.67 to S35 per ounce ... created an entirely new profit picture, and in

193-+, the mines were placed in operation and the old Trojan ~fining Company mill began treat­ing two hundred tons daily."63 With the new price, "profits soared, the two banks reco,·ered their original loan-the preferred stock was re-

The Bald i\1o11nlain i'vfi11ing Co!JijJtii!J 57

tired ~t p~r ~nd the comn1on stock p~id the b~nks nearl y $50,000 dividends; in the next ten years."6'

1

_-\ s the potenti~l to m~ke a pro fi t increased, Bald ~(ount·ain Mining Company improved its

mill recovery practices. T he plan t was converted "to an all-sliming counter-current decantation ~)l~nt] with ~ daily capacity of 350 tons."65 The

plant also roasted some of the dense refractory ores and, all told, these mill practices removed a second barrier to profit, permitting 80 to 85 per­cent gold recovery, whid1, in turn, " initiated a new round of activity."66

T he Bald Mountain Company primarily took oxidized refractory red o re from its Portland ~( ine. ~(ill operators processed this ore with a straight cyanide solution using an all-sliming pro­cess. T he only major changes in the extraction process at this phmt, compared to earlier cya­nide mills that reduced red ore, were the addi­tion of seven to eigh t pounds of lime per ton after the initial crush, and the use of a rotary vacuum filter for slime filltration. T he lime neu­trali7.ed the ore's acidity, aiding in the oxidation process. Three circul~r, continuous Portland til­ters were installed; these consisted of light metal frames, twelve feet in diameter, covered with a light cloth to remove the fine p~rticles from the slime. T he filters operat·ed in a slime vat, where vacuum pressure continuously forced the slime cl1rough the fi lter.67 'Ihese small changes con­verted the mill "to an alii-slime, coun ter-current de can ta tion plant. " 68

To work its underground mines and surface mill, the Bald i\[ount~in ~fining Company insti­tuted the contract labor system "to create incen­tive and stimulate interests" at the operation for

all jobs. T he company carefully studied mine and mill positions to es lt~blish a fair labor rate for ~ II , hence "very few objections were voiced by cl1e personnel." Tn the mine, employees were p~id 36.65 a foot for running the jackleg ma­chine th~t required mucking ~nd using the tr~m to move ore. .-\ man h and-mucking in a drift wit'11 a r~ise ~nd stope w~s paid $1.-1-0 for eYery

ore c~r he fi lled.69

_-\t first, only sm~ll amoun ts of blue ore were mined, and li ttle concern w~s shown fo r the low gold recovery from blue ore. Gradu~lly, blue­ore tonnage increased, until roughly ~ third of the ore processed daily at B~lcl Mountain was unoxidized blue ore. Faced with the reality of mining more blue ore in the future, Bald Moun­tain investors determined to add a roasting pro­cess based upon th e '1928 Bureau of ~(ines' tests. .-\ sa result of this decision, a roasting unit, crush­

ers, and drying equipment were purchased, ~nd the mill was remodeled, making th e Bald ~\ foun­

tain mill a technic~lly ~dvanced blue-ore treat­ment facility.

The first step in redes igning the plant's flow chart required separating the treatment of red and blue ores. The latter would be roasted, which was an added expense. Experiments at the Tro­jan ?\ fill, the South Dakota School of ?\ (ines, and the U.S. Bureau of ~\lin es had demonstrated the importance of roasting blue ore. The B~ld :.\(ountain ;\ [ining Company tried several com­mercial roasters, but none were satisfacto ry. That forced the company to design~ roaster spe­cifically fo r the blue o rcs from its mines. In 1937, the company, seeking simplicity and efficiency, constructed a rotating hearth roas1·er.70

Following prel iminary crushing, blue o re was discharged into a cylindrical drier four feet in height and twenty feet in di~meter. _-\fter dry­ing, th e ore dropped into a locally-designed, re­volving, donut-sh~ped roaster fifty feet in diam­eter. The roaster's revolving hearth was fired with natural gas and regulated to give the ore a ma.,imum roast of two hours at 620 degrees cen­tigrade. _-\fter roasting, th e ore dropped into a B~ker cooler measuring five feet in height and forty feet in diameter. Finally, the blue ore en­tered the same circuit as the red ore, ~nd was treated with a cyanide solution.71

By using the roaster and the ~11-sliming cya­niclc process, the Bald idoun t~in plant increased gold recovery rates from refractory ore-prima-

58 2006 i\lfi11i11g HiifOJY .JourNal

rily blue ore-from 20 to 80 percent. The large

furnace operated from 1939 to 19-tl o n highly refractory ore from the Two j o hns J\fine. When

the company reopened near the end of the war, the roaster was too expensive to operate, so all blue ore was treated only wid1 crushing and cya­

nide. But the secret the Bald i\fountain Com­pany had discovered was that "by using modern cyanide techniques, more of the blue ore can be treated commercially, without a preliminary roasting, when fine grinding is carefully main­tained," si nce fine grinding enables the cyan ide solution to dissolve the gold quickly.72

l'ine grinding of sands and slimes at 65 per­cent n1inus two-hundred mesh resulted in the largest percentage of gold recovered from the slimes. Even on Portland i\ [ine blue ores, fine

grinding worked better than a cheaper course crush, enabling more gold panicles to be exposed to the cyanide solu tion.73 Due to fine grinding, the cyanide solution dissolved 53.85 percent of the gold recovered in the crush ing circuit, with d1e rem.ainder recovered in d1e primary thicken-

ers (7.69 percent), agitators (19.23 percent), and secondary thickeners (19.23 percent).74

No twi thstanding these technological innova­

tions at the Bald i\lountain facilities, from 1934 to 19-t.2 d1e company benefitted from plentiful labor, and "high efficiency and supply costs (that] were reasonable." _\I though incorporating many labor saving devices, Bald i\ Iountain "continued to use the outdated hand labor methods until the mines closed in 1942"75 under d1e \\far Pro­duction Board's Closing Order T ,-208 requiring

the nation's gold mines to cease opcrations.76

\\fhen the company resumed operations af­ter the war, mine mechanizatio n improvements reduced manpower by 30 percent compared to 1941 . The "wage-supply cost inf:lationary spiral speeded up after 1950, and constant efforts had to be made to maintain cost of production." Pre­ventative maintenance reduced breakage, inno­

vatio ns improved efficiency, but increasing op­erating costs negated these measures and infla­tion accelerated after 1950. With ore reserves dwindling, the compan y lacked the capita l

Gold in the Mill Cir·cuit

Position in the Mi ll

Mill Feed Bowl Classifier Overflow Prima1y Thickener Underflow No. 1 Agitator No. 2 Agitator No. 3 Agitator No. 4 Agitator No. 5 Agitator No. I Secondary Thickener Underflow No. 2 Secondary Thickener Underflow No.3 Secondary Thickener Underflow No. 4 Secondary Thickener Underflow No. 5 Secondary Thickener Underflow No. 6 Secondary Thickener Underflow No. 7 Secondary Thickener Underflow

Gold in Pulp Ozs per Ton

0.150 0.080 0.070 0.065 0.060 0.055 0.045 0.025 0.040 0.035 0.025 0.040 0.035 0.030 0.020

Gold in Solution Ozs per ton

0.062 0.073 0.100 0.1 00 0.106 0.104 0.097 0.038 0.020 0.010 0.048 0.039 0.015 0.003

(From Miller, "Study of the Bald Mountain Mining Area," 97 .)

Tbe Bald Mo11ntain Mining Compa'!Y 59

needed to open new ore reserves. To make mf1t­ters worse, develo pment work had fallen "be­hind schedule and the outlook for a [goldJ price increase was poor."77

Based upo n these factors, the company dis missed emp loyees and redesigned its contrac1" la­bo r sys tem during its last five years of o pera­tions, but to no avail; the mine and mill closed in 1959.78 T he shutdown occurred so quickly that "everything was left o n company property, all tl1e tools in the machi ne sho p, office equip­ment, tiles, etc."79

To reopen tl1e mill, engineers would have to

improve the plant's technology. To improve clas­sification o f sands in th e secondary crushing cir­

cuit, a new and larger bowl classifier would have to be installed, since the current small classifiers did no t drop sands fas t· enough. Cone classifiers would have to rep lace the D orr rake classifie rs to improve overall sand and slime classification.

T he :tine precipita tio n metl10d would have to be changed to a new charcoal or resin pulp ion pre­cipitation. Last, greater auto mation would lower

cos ts, reduce human erro r, and provide mo re uniform gold recovery.80

T h e Bald Mo untain mines and the Bald

Mountain Mining Company were significant for two reasons. O ne was tlu t, des pite its ups and downs, th e Bald Mountain ?\fining Company be­came th e second largest gold producer in th e his­to ry of the Black H ills after the I lo mes take. Bald Mountain i\fining Company termina ted opera­

tio ns in July 1959, due to the low fixed price of gold ~md the steadi ly increasing cos ts o f running its mining and m illing o peratio ns, but from 193-J. un til 1959, it produced $13,9-l-8,720 in gold and ~628,-J.l l in silver, demo nstrating that th ere was mo re to mining in the Black Tlills than just the I-Jo mes take.81

T he o tl1er reason fo r tl1c company's place in

Tbe RoaJter - addition inteJiorjroiJI the S O!l!bJJ •eJt, JJ•ith a tieJJ• rf the mbble d1iz·e J"_JJiem. (F-TiJtoli,· Amelim11 E11gi11eeJi11g lZet·ord, Libmzy rf CongreJJ-.j

60 2006 Mi11i11g ;E-listoJ)' .foiiJ'JJal

mining history is that its operation represented the high point of blue-ore reduction technology in the era of underground blue-ore mining at Bald ;\ lountain. Technolog-ical and process innova­tions brought the company success. The Bald ;\lountain ;\lining Company returned profits for over three decades by mining and milling low­grade refractory red and blue ores and process­ing them with sophisticated roasting techniques, improved fine-crushing mach inery, and an evolved cyanide process. Through perseverance and innovation, management of the Bald Moun­tain ;\lining Compan)' and its predecessors mined and milled large quantities of low-grade blue ore for decades, creating a stable mining operation.82

Ultimately, the company could not produce adequate profits in the face of increasing oper­ating costs, in part because operating revenues cou ld not pay for added improvements after World \\ lar II. Even so, the Bald i\lountain ;\[in­ing Company was the most technically advanced blue-o re treatment plant to emerge from the Black H ills cyanide boon1, which began late in the nineteent"11 century and made the reg1on fa­mous for recovering gold from low-grade ores. Despite this, Bald i\lountain's mi ll never achieved the renown of the Lundberg, Dorr, and

\\' ilson cyan ide mill at Terry, where Dorr in­vented machinery that improved gold recovery from the cyanide process throughout the world .

_-\Jthough neither the region's largest nor most celebrated enterprise, Bald i\£ountain was the most technically interesting gold recovery opera­tion in the Black Hills. It proved that the region's metallurgists and mill engineers could develop blue-ore recovery practices from laboratory ex­periments into profitable operations. The next cyanide boom, in the 1980s, was made possible by heap leaching, with it·s massive open pits, ore pi les, and leach ponds that forever ended the era that the Bald Mountain ;\ fining Company repre­sented . .Jill.

Ridw;oNd L. Cion; a nafit-e of S outb Dakota, is prqfeJSor qf Natit-e A11mim11 Studies at the Ulltt"CJ"­sity of 1\lfol!talla i11 MiJSoula. He m·eit·ed his dodOJ"­ate i11 biJtory from the U11it·miry qf Nell' Nk\:im i11 1971. Hi.,- 1-e.,-eanl; iutemts i11d11de B!a~·k T-TiiiJ· IJiiJJ­iug aud mi.lliug history, and be is tbe a11tbor if Chas­ing the G litter: Black Hills Milling, 187-J.-1959, a history if tbe region's gold J -e~·oa1y p1omm.

Nottes:

1 J V. 1 . Dorr, "South Dakota," E11gi11eeJi11g a11d 1'1i11i11g }ollma/89 (1910): 92-3.

2 J ames .J. Norton, "Bald J\lountain Gold Mining Region, Northern Black Hills, South Dakota, U.S. Geological SULvey, Opc11-Fifc Rcpo!t83-791, 1983, 1.

3 Norton, "Bald Mountain Gold J\lining Region," 1. "' Charles L. Hummel, "The StLUcnu·e and Mineralization of

a Portion of the Bald J\Iountain !\lining District, l.awrence County, South Dakota" (master's thesis, South Dakota School of Mines, 1952), 6.

5 H. \'i/. Chance, 'The Discovery of New Gold Districts," Tra11Sadio11s of tbe A meli((/ II l11sltfllle of 1Hi11i11g E11gi11eerJ 29 (Feb. 1900): 225, 229.

6 P. _-\. i\ liUer, "_-\Study of the Bald J\Iountain !\lining _-U:ea, Lawrence County, South Dakota" (master's thesis,

South Dakota School oH.lines and Teclmology, 1962), 5 . .Julius .-\ttila, "Black Hills Gold 1\ lining, l876-193:i: Toward a Time-Space J\Iodel" (Ph.D. diss., University of Oklal10ma, 1979), 89, "102.

7 1\ttila, "Black Hills Gold !\lining," 89, 102. 8 _-\mil _-\. _-\nderson, "Cambrian Blue Siliceous O res of the

Black Hills," Pa!Jasapa Q11m1e1~·4 (Feb. 1915): 18-9. .Joel K. Waterland, Gofd & Siircr or Sweat & 'femY: Tbe Hislo~y of tbe Bald 1\1omtlain, R111!J' Basin rmd Garden Ci()• Mining Diftlic1J(Grelind PhotoG raphics & Typesetters: Rapid City, SO: 1988), 141.

9 Frank Clemes Smith, "The Potsdam Gold Ores of the Black Hills of South Dakota," TrmtJadionJ of tbe Ame1itan Jnsti1111e ofl\li11i11g E11gi11eers 27 (1898): 420-5. H. 1\ L Clumce, "Gold Ores of the Black l~Llls, Soutl1

'J be Bald Mom;tain Mining Co171fJtii!Y 6'1

Dnkotn," Trai/Stlt'fiolls of the Amm'm11 f11stit11te of Jlli11i11g E11gi11een 30 (1900): 280- 1. \\laterhUld, Gold G"' Slirer or Sweat G"' Tears, 141 !\ Iiller, "Study o f the Bald 1\lountain Mining .-\rea," 6.

Miller, "Stud~· of the Bald 1\ (ountain Mining .-\rea," 6. \\'atcda.lld, Gold C.:.."' SilrerorSweat &TeaJ:i, 77-80.

11 Smith, "Potsdrun Gold O res," 420-5. Chance, "Gold­O res of the Black !!ills," 280-1. \\1aterlru1d, Gold G"' Si!l'l!r or Sweat G"' Tears, 141.

12 H ummel, "Structure ru1d Mineralization," 6. Smith, "Potsdam Gold Ores," -120-Ci. Clumce, "Gold O res o f d1e Black Hills," 280-1. \Vatcrlru1d, Gold C..."' S1irer or Sweat & Tean~ 14'1. Chm·les H. Fulton, "Crushing in Cyru1ide Solution, as Practiced in the Black Hills, South Dakota," Trrmmdio11s of the Ame1im11 lmtit11te of Mi11i11g Et{gi11em 35 (1905): 6 '15. .Joseph P. Connolly, 'The Tl'rtillt")' i\ linPmli zMion of the NorthPrn Rl~ck l lills," South Dakota School ofi\lincs ru1d Technology Rlllletill 110. 15 (Rapid City, 1927): 76. C. G. \\larnford Lock, "Gold Mining and 1\ lilling in the Black Hills (S. Dakota)," TraiiJflt'fioiiJ of the Jmtit11tirm of Mi11i11g a11d Meta!IIIIJ!)' 3 (189-1-5): 31. Anderson, "Otmbrian Blue Siliceous Orcs," 18.

13 Chance, "Gold Ores o f the Black Hills," 280-1. foul ton, "Crushi.11g i.11 Cyru1idc Solution," (>15. Smit·h, "Potsdrun Gold O res," 426. Connolly, ''I'e rtiar~·

1\ lineraJization," 76. Lock, "Gold !\lining and 1\ lilling," 31. _·\nderson, "Crunbrian Blue Siliceous O rcs," 18.

1" Mi ller, "Study of the Bald 1\lountainl\lining .·\rea," 92.

15 Chru1ce, "Gold O res of tJ1e Black Jlills," 280-1. Fulton, "Crushing in Cyru1ide Solution," 6 15. Smith, " Potsdrun Gold O res," 426. Connolly, 'Tertiary Mineralization," 76. r.ock, "Goldl\Liningand i\lilling," 31 . :\ndcrson, "Cambrian Blue Siliceous Ores," 18.

Despite the difficulties associated with recovering gold from the refractory orcs, the Horseshoe Mining Company was reorganized as the 1\Iogul l\ lining Company in1905 and consolidated ru1 "area extending from the eastem boundary o f the Portland District, to and including, the Ben Hur Mine." Hummel, "Structure ru1d 1\lineralization," 6. For a study of the fraud associated with the Horseshoe, consult David .\. \\lolff, "No !\fatter I low You Do It, Fraud is Fraud: .-\nother T .ook at Black Hills i\ fining Scandals," S'o11tb Dakota HisiOI)' 33, no. 2 (Sum. 2003): 91-119.

16 forru1k Clemes Smith, "The Occurrence and Behavior of Tellurium in Gold O res, i\Iorc Particularly wid1 Reference to the Potsdam O res of the Black Hills, South Dakota," Tra11sat'tiow of Amelim11 li1J1it11te of iHi11it{g E11gineers26 (1897): -185-515, II 05.

'' B. D. O'Brien, "Cyaniding Black Hills 'Blue Ores,"' Mims n11d Mi11em/s 29 (. \pr. 1909): 431 .

15 Dorr, "South Dakota," 92-3. For rhe best study of the men who worked the Homestake and the fmnous lockout see Joseph H. Cash, lli'orkit{g the HoJJ/eJtake (.·\mes: Iowa State University Press, 1973).

19 \\'aredru1d, Gold GN S'ilreror Sweat 6"" T'ecrrs, 141. 2l H ummel, "Structure ru1cl Mineralization," 7. 21 Hummel, "Structure and i\lineralization," 85. C- Jesse Simmons, "T rojrul Cpulicle Mill, Black r Iills,"

EngilleeJit{g and i\1illli(g ]ollma/92 ('19 ;\ug. 1911): 357. • 3 Miller, "Study of the Bald Mountain Mining .-\rea," 92.

\Vaterland, Gold & Silreror.}weat GN Teti!J, 141. ·" _-\llderson, "CambriaH Blue Siliceous Ores," 18-31. 25 Connolly, ''I'ertiarr Mineralization," 78-9,87-90. 2

(, Connolly, 'Tertiary i\fineralization, "427-31. "

7 C. G. \\Iillard, "The Golden Reward Roaster," Pabasapa Q11m1er/)• 5 (June 1916): 40-5.

" 5 l.onnolly, " I'Prtiat-y ,\linPritl iz~tion," -127-1 1. \\liii:IITI, "Golden Reward Roaster, 40-:i.

. Y Connolly, 'Tertiary .t\ lineralization," 427-31. Willard, "Golden Reward Roaster," -10-5.

3 ' \Vi llard, "Golden Rcwllrd Roas ter," 40-5. Connolly, 'Tertiary t\Lineralization," 76.

31 Lawrence B. \\'right, "Gold Deposition in the Black I lills of South Dakota lmd Wyoming," 'fi rmsat'tions of t/;c A111mi:a11 Tn.rtit11te of i\Ii11it{g a11d i\1etallmt,it'af E t{gilleCJJ' l2(i (1937): 412.

31 Joseph P. Connolly and Cleophas C. O 'Harra, 'The 1\lincral Wealth of the Black Hills," South DRkota School o f 1\ lines and Technologr, BlllletillllO. 16 (Rapid Ci~·, 1929), 164-6.

33 Connolly and OHarra, ''i\ lineral Wealth of the Black I-Iills," 1 (>4-6.

3" "South Dalmta," Et{gtiteetit{g a11d Millingjoumaf99 (1915): 512.

3~ \Vaterland, Gold G"' St!rer or Sweat c> TcatJ, 87. ·' 6 Jesse Simmons, "!\ lining in South Dakota 111 1914,"

Et{gilleeJit{g a11d i\1titit{g]OIImal99 (191 5): 99. 37 "i\ [ining in South Dakota in 1919," Et{gilleetit{g a11d Mimi{g

]ouma/109 (1920): 142,677. 38 "Trojan !\ fining Co. Burs Holdings of Ofer Company,"

Et{gilleetit{g cmd Mi11i11g ]o11ma/11l (1921 ): 480. 39 "Trojan Will Resume Development of South Dakota

Gold Propert:·," Dl{gilleelit{g a11d i\1illit{g./OIImaf-Press 117 (1924): 182.

"' 'T roj ru1 Compru1y Suspends Mill Operation at Dead­wood, S.D.: New Ore Will Be Developed ru1d 1\lill Remodeled-No Profit Under Present Conditions," Et{gilleeni{g a11d Mtitit{g]OIImaL-PtlJSS 11:; (1923): 333.

" 1 \\'atedand, (;old & .'lilrerorSweato....,Tears, 141. " 2 Hummel, "Structure and Mineralization," 67. '' 3 Robert E . Driscoll, .'lerell()' 1 -ecrrs of Ba11kit{g i11 tbe Blat'k

Jli!!s: Fim National Ba11k of the Rlatk Hi/Lr, 1876-19-+6 (Rapid City, SO: Gate City Guide, 1948), ?.f.

62 2006 lvlining 1 liJ'tory .fo;mltl!

"" Connolly and O'Harra, "Mineral \Vealth of the Black Hills," 164-6.

" 5 Connolly and O'f Jarra, '';\ lineral \'i'ealth of the Black

Hills," 164-6. "

6 Edmund S. Leaver and Jesse :\. \Voolf, "Cputide E xtraction of Gold and Sih·er . \ ssocimed with :\rsenic and .-\.ntimony i.n Ores with Special Refe rence to Those in Nevada and South Dakota," U.S. Bureau of I\ lines Ted)lfiml Paperno. +23 (\X'ashing ton, D. C.: U.S.G .P.O ., 1928), 3, 23,25-6,33, 37, ~2-3.

•' Leaver lUld \Voolf, "Cym1icle E xtraction," 3, 23,25-6,33, 37,~2-3.

•s Leaver and \\'oolf, ''C~·anide Extraction," 3, 23,25-6,33, 37, ~2-3.

•Y !\ filler, "Study of the Bald ,\!ountain i\lining.-\rea," ~6. 5

' "Troj;m !\line to be Reopened," Hnginming and Mining ]o//!7/(/l, 126 (1928): 76'1.

)I Frank Herbert, +0 ) ·ears ProJpec1ing and Mi11i11g i11 lbe Bltltk 1-/t!IJ· q[Joutb Dakota (Rapid City Journal: Rapid City,

1921), 197-8. 52 D riscoll , Serm(J•} ·emJ q[Ba11king, 74. 53 Simmons, "Trojan Cpmide i\lill ," 357-8. Driscoll ,Jerm(J•

YearsrfBrmkillg, 74. N . P. Goodrich, "~tilling Practice of the Bald i\[ountain i\lining Company," T rojan, S. D., Black I lill.s Engi11eer 23 (lm1 1937): 173. Paul T. :\ lisman, 'Reconnaissance of Gold-.\ lining Distric ts in the Black I-Tllls, S. Oak.," U.S. Bureau of !\lines B11lleti11 110. +27 (\VashiJlgton, D. C.: U.S.G .P.O ., 1940), 27.

5" Driscoll , Semi()' YetiiJ o/ Ba11king, 7-1-.

55 Hummel, "StLUcl11re and i\lineralization," 7. 56 \Vaterhmd, Gold & Si!rer or Jn:eat G"' Ter11J, I~ I. 57 "Tro jan i\line to be Reopened," 76 1. ss "Trojan i\line to be Reopened," 761. Simmons, "Trojan

Cyanide i\lill," 357-8. Driscoll , Semi()' 1 'ean q[BaHki11g, 7~. Goodrich, ".1\lilling Practice," 173. :\lisman, "Reconnaissance ofGold-i\lining Districts," 27.

s9 \\iate rland, Gold & Si!nr or Jl/'eat & Tean, l.f l. 60 Donald H. i\lcLaughlin to B. C. Yates, Lead, Soutl1

Dakota, 4 July 1929. Cover lette r to "Preliminary Report on the Golden Reward :mel .1\Iogul Properties, Bald l\[ountain D is trict, South Dakota," in the University of Califo rnia Library, Berkeley, Califomia.

61 !\lining companies claimed that gold recoverr profits would iJJCrease if the gold st;Uldard were eliminated. See "Reducing Costs by . \b:u1doning the Gold Standard,'' U.ngineeling rmd Jllini11g ]o11mal 133, no. 1 (Jan. 1932): 1 -~.

6: Simmons, 'Trojan Cyanide i\lill ," 357-8. Driscoll , Serm(J•

l"etuJq[Bt~Hkillg, 14. Goodrich, "~ulling Practice," 173. _ \Jlsm :Ut, 'RecOilllaim mce of Gold-l\w1ing Districts," 27.

6.l Watcdand, Gold &Ji/rerorJII'etlt G"'TemJ', 1~1.

6" Driscoll, Sereii{J' 1 em)· o/ Brmki11g, 74.

6~ ~diller, "Srudy of the Bald ,\[ountain .\lining :\rca," 93. 66 I Iummcl, "Struc ture and i\ lineralization,'' 67. 67 Goodrich, "i\lilln1g Practice," 174. • \. L. Slaughte r,

"!\ fining FIM Formation Gold Deposits at the Bald i\lountain ~w1ing Comp:u1~·, Trojan, South Dakota," B!rlt'k Hills b~,gineer23 (lan. 1937): 164.

6~ \\'atc rland, Gold G"' Si!rerorSweat G"' Tem"J·, '141. 69 l\lillcr, "Sn•dy oftl1e Bald .\[ountain ~lining Area," 103-6. '~ i\ liller, "SniCly of the Bald i\ lounmin ,\lining . \rea,'' ~6. 71 :\lisman, '·Reconnaissance ofGold-l\ fining Disrricts,'' 30,

33-.f. 72 l\ Iiller, "Study of the Bald 1\ lountain i\lining .-\rea,'' .fo-R,

98. 73 \\'right, "Gold Deposition in the Black Hills,'' 412. '• i\ fille r, "Stuclyofthe Bald i\ lountain l\ fining :\rea," 97, 98. ~ i\liller, "Study of the Bald .\lountain i\lining:\rea," 101-2.

'6 South Dakota Inspector of l\w1es, Fif()•-Senmtb Amwal

Rep011 o/ tbe T11spet1or o/ Jlli11es Q)ie rre: State of South Dakota, 1959), 9.

'7 l\ lille r, "Sn•dy of the Baldl\lountain !\lining . \ ren,'' 102.

•s J\lillcr, "Sn•dy of the Bald J\lountain !\lining :\rca,'' 102. '9 Ken Stewart, letter to author, 26 Feb. 2004, in author's

possess•on. •· •\lillcr, "StudY of tJ1c Bald ~lounrain i\wtiHg.-\.rca,'' 118-9. 81 Inspector of !\lines, Fif(J•-Jmmtb A111111al Repo11, 9. 5

" I .awrcnce Coun~· Historical Socie~·. So111c f-lislol)' o/ Ltm'l'l!lll<' Coli II()' (Pierre, SO: Lawrence COLmty I lis tori cal Societr. 1981), 550.