Idaho History July 16, 2017

Thunder Mountain Gold Rush

(part 1)

1901 First Cabin at Thunder Mountain


source: Earl Willson, The Thunder Mountain Story, Thunder Mountain, “Tome Up”
(personal collection – h/t SMc]
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Idaho and Thunder Mountain

By A. E. Borthwick, Boise, Idaho

Excerpted from the Official Proceedings of the Fourth Assembly International Mining Congress Held at Boise, Idaho, July 23, 24, and 25, 1901

As a sample of some of the wonderful riches the state contains, a brief description of one district is here given:

Through the operations of a short mining boom in 1901-02, Thunder mountain has become known all over the country from Maine to Oregon as a remote mining locality in central Idaho. In some places, no doubt, the opinion is held that it is a good place to stay away from.

Thunder mountain lies a little south of the 45th parallel of latitude, and almost on the 115th Western meridian line. The mining district of that name comprises the country around it for perhaps thirty miles in every direction. No surveys have been made, and few maps indicate the exact locality. The district is new, very large, and, judging from the comparatively small amount of development work done thus far, is very rich. It is situated on the top lines of the watershed draining northerly into the Salmon river. The altitude is not as high as Cripple Creek and many rich camps in Colorado. None of the higher peaks reach quite 10,000 feet; the general average of the ridges being from 7,500 to 8,500 feet.

The country is very rugged and the mountain sides steep. Slide rock is common.

In no direction is there scarcity of wood or water. Grass is plentiful in its season. There are large areas of burned timber, but generally there is abundance of timber. Valleys are narrow; seldom a quarter of a mile wide. Winter is long, but not severe. The thermometer showed 16 degrees below zero once last winter; a number of times it was 10 degrees and 12 degrees below zero. Snow commences to come from November 10th to 20th., and is three feet deep on the bottoms, to six and eight feet on the ridges. It is off the southern slopes in April, and grass starts at once. May 1st shows the creek bottoms bare of snow and blooming.

The placer mining operations of the Caswells, with the subsequent sale of their holdings on Thunder mountain to Colonel Dewey, of Nampa, Idaho, followed by energetic operations, started the mining boom in 1901-02. Thousands went in and claims were staked covering the porphyry field for nearly twenty miles in all directions. Of the thousands who went in, a few hundred saw the probable future wealth to be had and remained. Of the thousands of claims that were staked and recorded a few groups have been developed, enough to indicate the ultimate richness and greatness of the district.

In the narrow valley of Monumental creek, at the mouth of Mule creek which drains the Dewey property, and about midway between Thunder mountain and Rainbow peak, a town was started, named Roosevelt. To the West the nearest wagon road was seventy miles, and to the South eighty-five miles.

As prospecting went on it was found that much of the surface porphyry which covers a large part of the territory, was either barren or yielded but a small amount of gold, also that in a marked degree there was an absence of ledges or veins or walls which the prospector considered essential to ore production. In some places the surface rock would show colors in panning, and the earth on some of the higher hills would exhibit a generous streak of yellow to those who took the trouble to carry the dirt to water. Usually there was little systematic work done, and a few days, or weeks, at most, brought a reversal of sentiment and the average gold hunter and rainbow chaser had left the country before the winter of 1902, reporting it “no good.”

Last year saw a continuation of the development with good results in every instance where the work was intelligent and careful, and sufficient to place it beyond the assessment condition.

The main porphyry field extends from the top of White Pass, six miles south of Roosevelt, on both sides of Monumental creek, to the mouth of Holy Terror creek six miles below the town, and includes Thunder mountain and Rainbow peak, with one or both slopes of Marble and Cottonwood creeks on the East and South, Sugar and Tamarac creeks to the West of Rainbow, the West Fork, and well up Snow Slide ridge to the North. This embraces in the main area a tract about twelve miles square, of which fully twenty-five per cent. (and I think more) is porphyry or quartz-porphyry. There are other small porphyry fields down Monumental, Marble and other creeks.

Within the area described extensive development has been done on less than a dozen properties, The Sunnyside company on the slope of Thunder mountain has pursued a plan of development wise, careful and systematic, that has been productive of remarkable results. Within about two years, by working perhaps an average of twenty-five men, its superintendent gave in December last a conservative estimate that there was fully 500,000 tons of ore in sight that will mill from $7.00 to $10.00 per ton. This company is now working 250 men and is installing a forty-stamp mill with overhead tramway about a mile long, and will soon be a producer of bullion. The cost of mining and milling is estimated at below $1.75 per ton.

The Dewey has done even more development work. After milling ore all winter with its ten-stamp mill, having no delay or annoyance from ice or snow, it closed down April 1st, from shortage of wood supply. Its March run produced more than $20,000 gold bullion from its batteries and plates.

The H. Y. management commenced development on the southwest slope of Thunder mountain after acquiring the property last fall, and this spring in the face of its tunnels after going 200 and 300 feet got values from $50.00 to $70.00 per ton. While in the whole length of the tunnels the values had averaged $4.00 to $6.00 per ton.

It will take many years to tell the story of the extent of the pay ore bodies.

The above are samples of what has been found on partial development. In such a large field showing relative sameness of surface values, where commencement of tunnel work is determined by the relative steepness rather than by any superior surface showing, it is not likely that the present developments include all the good ore bodies that will be uncovered. It is the general expression of those conversant with the conditions, that the present companies’ great finds will be duplicated by many others, and even richer fields opened as the work of exploration goes forward.

The developments on Rainbow peak have not been so extensive as those on Thunder mountain proper, but the Fairview developed a dike about forty feet wide, nearly 3,000 feet in length which is reported to average above $8.00 per ton, free milling. The Toronto, Gold King, First National, Tripod and others are finding good ore values as the work progresses. Very good values are reported on Sugar creek and Tamarac creek to the west of Rainbow, also on Divide, Coney, Four Mile, Lava, Cornish and Cottonwood creeks south of the Monumental and Thunder mountain, and on Trap, Rainbow, Botha, Bonanza, Sable and southwest fork of Monumental to the north of that stream. Active developments are being made on Big and Little Indian, Marble, Holy Terror, Doer and Rush creeks, with satisfactory results.

The Big Creek district to the northwest is another rich field, receiving much attention, and showing great ledges of free and base ore of remarkable size and richness.

Following are expert opinions:

Hon. M. H. Jacobs, ex-state mine inspector, who has frequently visited the district, says –

“The time has gone by when anybody of however doubtful a nature he may be, can say that the mines in and about Thunder mountain are not going to make great producers.”

Professor D. H. Mead in a report to the Oregon Short Line Railway Company, says in part –

“In reply to your question as to what were my impressions of Thunder mountain, will say that it is an immense reef of rhyolite, porphyry and breccia, averaging $6.50 per ton, in such great quantities that in the short time I was there it was impossible to estimate extent.”

This relates to the Dewey property which at present is the only mine where any great development is being done, but enough ore shows to keep a hundred-stamp mill going indefinitely. When properly equipped ore can be literally quarried out on the same principle as the Homestake in the Black hills and Treadwell mines of Alaska. An unlimited electric power can be developed on Monumental creek, a distance of eight miles from the mines. Timber and water are in abundance. The formation of the ore is principally porphyry-rhyolite-trachyte and phonolite.

William Allen White says –

“Gold mines and gold prospects on Thunder mountain proper are located in porphyry reefs and intrusive dikes of talc. These reefs and dikes occur in steep dust-covered hills, soft in outline and about 3,000 feet above the gulches about them. The ores are found free in porphyry or talc, with little quartz and few crystals. It is a comparatively low grade ore, but is found in large streaks and pockets, and seems to be running richer in values as the tunnels go in, for the gold appears to be coming from below rather than to be a sedimentary deposit.”

Professor E. J. Conroy of Boise, Idaho, says –

“Thunder mountain is a vast area of porphyritical upheaval. The soft rocks of this formation have been scored to great depths by streams draining this wide area, and the sides of the canons are very precipitous. It would seem that the whole area was a lake bed, and some violent convulsion of nature caused this vast upheaval of porphyry, that the subsidence occurred immediately before the waters had receded, and that gold had been disseminated along the strike of the vast dikes of porphyry, enriching areas of the uplifted rocks.”

William E. L. Hame says –

“I consider the formation identical with that of Cripple Creek. It consists of rhyolite, intersected by phonolitic intrusions. The greatest values are met with at the contact of the dike with the overlaying volcanic breccia.”

I quote from report of Charles Raymond, M. E., of Chicago –

“One remarkable feature in regard to the Thunder mountain district is that the ore bodies throughout the district are identical. In other districts ore is found in many different forms. While work has been carried on in some of the leading properties to the depth of over 200 feet, and cross-cut tunnels run in opposite directions, no well defined walls have yet been encountered, going to prove the assertion often made that Thunder mountain is one vast mountain of ore.”

These gentlemen reported their findings eighteen months to two years ago.

J. M. Venable, a well-known mining superintendent, who has spent much time in the Thunder mountain district, and given careful attention to the occurrence of ore bodies there, holds that the veins do not crop their course, being simply indicated by changed conditions of the rhyolite or porphyry. Where the rhyolite or porphyry shows quartz crystals, some gold is met with, and at all such points where the surface rock has been cut through, ore bodies have been found.

Professor E. M. Ray, former superintendent of Stratton’s Independence mine at Cripple Creek, Colorado, says in part in a recent interview in the Idaho Statesman, July 14th, after his third visit to the camp –

“The development assures the camp a place among the richest in the country. I feel justified iii saying so much as that, and I might add that in my opinion the district is likely in two or three years to be better than Cripple Creek is or has been.”

Of the general mass of porphyry, Mr. Ray said –

“It averages higher than the ore of the Treadwell mine. I have taken a great many samples and find the average some where between $2.75 and $3.50. It is absolutely free milling and can all be handled at a good profit with sufficient milling capacity.

“The great feature of the camp next to the size of the ore bodies,” Mr. Ray continued, “is that the ore is absolutely free milling. Plates only are needed. You do not have to have concentrating machinery or anything else be yond the batteries and plates. There is no base in the ore, and the values can all be saved by simple amalgamation.”

More than likely the great mass of ores are as described by Professor Ray. There are some sulphides, however, in the mysterious Slide group adjoining the Dewey, and in the tunnel of the Dakota claim of the H. Y. group.

Lack of transportation has been a serious handicap in development of the district. With nearly one hundred miles of rough trails over which everything had to be packed, costing from six cents to ten cents per pound, it took a rich country to justify the expense of even surface prospecting.

The completion of the wagon road now assured will revolutionize former conditions, enabling the Thunder mountain country to be easily reached about every month of the year and contribute largely toward opening an era of prosperity there, whose benefits will be lasting and far reaching.

excerpts pgs 39-45: 1901 Official Proceedings of the Fourth Assembly International Mining Congress.pdf (19 mg) (google book)
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No Place for the Poor Man

Colorado Springs Attorney so Speaks of Thunder Mountain.

Walked the Country O’er

Says There is Wealth There But it Will Require Capital to Develop It – Boise Booming

The Deseret News September 19, 1902

I.T. Jones, an attorney and mining operator of Colorado Springs, arrived in Salt Lake this morning from Thunder Mountain. Incidentally Mr. Jones proudly boasts that this summer in Idaho he has walked more miles than there are miles of railroad track in that state. As there are 1106 miles of railroad in Idaho, it goes without saying that Mr. Jones has worn out several pairs of shoes this summer.

“I thought that the best way to see the country was to walk,” he said this morning, “so four companions and myself got a pack train for our outfit and we walked into Thunder Mountain from Boise, a distance of 210 miles, and arrived there June 9. We made our headquarters at Roosevelt, from which center we thoroughly explored the country on foot. We started out of the district on the 15th of Last month.”

Mr. Jones in summing up the situation said that Thunder Mountain district was no place for the poor man. But for the capitalist with the money to put in for development, he was confident there was wealth practically in sight. He stated that the formation around Thunder Mountain proper consisted of a light talc with a porphyry blanket over it which eventually runs into a sugar quartz. The porphyry formation runs from $2 to $8 a ton, and can be treated for $1.60 a ton, all free milling. Most of the ore in and around Thunder Mountain proper is of a low grade order and can be treated by stamps or cyanides. Within a radius of 25 miles the porphyry disappears and immense quartz ledges crop to the surface. On Profile creek Mr. Jones said he followed one ledge for 15 miles which averaged 40 feet wide, and in places was 400 feet wide on the surface. Various assays of this ledge had been made, one showing 300 ounces of silver and one of gold, while another showed one ounce of silver and six ounces of gold to the ton.

For 30 miles around Thunder Mountain the country is mineralized, but its inaccessibility makes development slow, although there are abundance of water and fuel.

In answer to a question as to how many people there were in the district Mr. Jones said that when he left the postmaster informed him at Deweyville that he had mail for about 3,000.

Mr. Jones said that men were constantly coming into the district and leaving it, and many would spend the winter there.

Considerable good properties had been taken up by syndicates and Mr. Jones expressed himself of the opinion that all the “knocking” done in the numerous papers throughout the country had been instituted at the instigation of the syndicates which were interested and desired to keep prospectors out until they had got the pick of the district.

In speaking regarding Boise Mr. Jones said:

“Boise is a good town and I intend to settle up my affairs and return there in about two weeks. There is not a cottage for rent in the whole town and although three business blocks are now in course of erection there every office has been spoken for. I regard Idaho as being the state in the Union which has more opportunities for the young man than any other, and I intend to make it my future home.”

source: The Deseret News September 19, 1902
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Thunder Mountain District


source: Earl Willson, The Thunder Mountain Story, Thunder Mountain, “Tome Up”
[personal collection – h/t SMc]
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Valley County Idaho Gold Production

By A. H. Koschmann and M. H. Bergendahl – USGS 1968

Valley County, in west-central Idaho, was formed in 1917 and is one of the newest counties in the State. The early gold production of the area now known as Valley County was reported under Idaho or Boise Counties. Staley (1946, p. 28) credited Valley County with 96,578 ounces of gold from 1917 through 1942. Total gold production from 1917 through 1958 was 324,460 ounces, most of which was mined from lode deposits of antimony-gold ore in the late 1940’s. The gold districts are in the northeastern part of the county in a triangular-shaped area with Edwardsburg at the apex and the Yellow Pine and Thunder Mountain districts at the southwest and southeast corners respectively. Each side of the triangle is about 15 miles long. Edwardsburg, however, had only minor gold production and will not be discussed here.

Thunder Mountain District

The Thunder Mountain district is in T. 19 N., R. 11 E., on Monumental Creek, in northeastern Valley County.

Discovered in 1896, the Thunder Mountain district is a typical example of the effect of rumor on the gold-fever-ravaged minds of that day. Accounts of wondrously rich gold ore attracted several thousand people to the district in 1902, and the towns of Belleco and Roosevelt sprang up; Roosevelt was the principal business center (Shenon and Ross, 1936, p. 18). The boom lasted until 1907 when the principal producer, the Dewey mine, closed regular operations. In 1909 a landslide destroyed the town of Roosevelt, and this disaster stifled the enthusiasm of those still remaining in the district (Shenon and Ross, 1936, p. 19). After 1909 there were only intermittent operations in the district, chiefly at the Dewey and Sunnyside mines.

The total value of production of the district to about 1940 was $400,000, most of which came from the Dewey and Sunnyside mines (Ross, 1941, p. 96). Although most of this was in gold, silver was also important as evidenced by the Dewey mine production record of 14,342 ounces of gold and 8,484 ounces of silver from 1902 to 1919 (Shenon and Ross, 1936, p. 38). Total gold production of the district through 1959 was probably about 17,500 ounces.

Bedrock in the Thunder Mountain district consists of tuffaceous and rhyolitic rocks interbedded with sandstone, shales, and breccias, all considered part of the Challis Formation of late Oligocene or early Miocene age (Shenon and Ross; 1936, p. 10). Locally, patches of basalt cap the higher areas.

The ore bodies are in altered rock, usually in the more permeable beds; at the Dewey mine, for example, the ore is in altered rhyolitic tuff, sandstone, rhyolitic lava, and breccia, in a steeply dipping shear zone. Pyrite and pyrargyrite were the only recognized ore minerals, and the gold was associated with pyrite irregularly concentrated in the rocks. The host rocks are highly silicified (Shenon and Ross, 1936, p. 39). At the Sunnyside mine the ore occurs in flow breccia overlain by interbedded sandstones, shales, and conglomerate; a mudflow overlies much of the area. At some places where the mudflow is close to the breccia, blanketlike ore bodies are formed. Apparently the mud acted as an impermeable barrier to the upward-moving ore solutions. The ore is highly oxidized although patches of pyrite can be found locally.

Yellow Pine District

The Yellow Pine district is between lat 44°50′ N. and long 115°00′ and 115°30′ W., near the town of Stibnite.

In about 1900, during the rush to the Thunder Mountain district, deposits of quicksilver, antimony, and gold were found in the Yellow Pine district. No work of any consequence was done, however, until 1917, when the demand for quicksilver encouraged development of several properties, notably the Fern and Hermes mines (Cooper, 1951, p. 152). Gold-antimony deposits were developed in 1929 at the Meadow Creek mine, but this property was closed in 1938. The Yellow Pine deposit, the major producer of the district, was discovered in the early 1900’s but was not mined until 1937. At first only gold and antimony were recovered, but in 1941 scheelite was found. Activity accelerated, and during World War II the Yellow Pine mine became the largest tungsten producer in the United States. The tungsten ore was exhausted by 1945; nevertheless, large-scale mining of the antimony-gold ore continued (Cooper, 1951, p. 174-175). At the end of 1952, the Yellow Pine mine was shut down and virtually no gold was produced from the district afterward. The nearby town of Stibnite was almost deserted by 1958. The Hermes mine remained active, however, and was still producing mercury in 1959.

The gold production of the Yellow Pine and Meadow Creek mines through 1945 was 101,437 ounces (Cooper, 1951, p. 155). Little if any gold was produced from any of the other properties. Total district gold production through 1959 was 309,734 ounces.

The oldest rocks in the Yellow Pine district are quartzite, quartzitic conglomerate, mica schist, altered limestone, dolomite, and tactite, all probably Ordovician in age (Cooper, 1951, p. 156). These rocks were folded and faulted, then intruded by a mass of quartz monzonite related to the Idaho batholith of middle Cretaceous age. There was also some postintrusion faulting that dislocated the igneous rocks (Cooper, 1951, p. 162-163). Dikes ranging from basalt to rhyolite in composition cut the quartz monzonite and fill many of the faults and shear zones.

Ore deposits, according to Cooper (1951, p. 164), are of two types: deposits of low-grade disseminated gold ore containing local concentrations of antimony, silver, and tungsten; and deposits of quicksilver. Currier (1935, p. 16-17), on the other hand, classified three types: arsenical gold ores, antimony-gold-silver ores, and mercury ores.

The gold-bearing deposits are characterized by auriferous pyrite and arsenopyrite, scheelite, and stibnite. Cooper (1951, p. 165) noted a zoning of the deposits. East of a north-south line, 1 mile east of Stibnite, only mercury deposits are found; west of the line the important tungsten-antimony-silver-gold deposits are found. All deposits are localized along faults; the zoning is probably due to depth below the land surface at the time of mineralization (Cooper, 1951, p. 165). Most of the deposits consist of a network of small mineralized fractures and disseminations in the adjacent wallrock.

source: July 16, 2009 Western Mining History

Link: Thunder Mountain / Roosevelt History index page

page updated October 26, 2020