By A. H. KOSCHMANN and M. H. BERGENDAHL - USGS 1968
Many districts throughout Idaho County - such as Buffalo Hump, Dixie, Elk City, Orogrande, Simpson, Tenmile, and Warren-Marshall - have made the county the second largest producer of gold in the State.
The first gold discoveries in this general area were made in 1857 along Orofino Creek, in what is now Clearwater County, by Jean deLassier, a trapper. Later, E. D. Pierce made the well-known discoveries at Pierce, and a rush to the region followed. By 1861 a group from the Orofino area explored the unknown country to the south and found placer gold along the South Fork of the Clearwater River at Elk City, in what is now Idaho County. In a few months more than 2,000 people rushed to the new area.
Other discoveries were made in 1861 at Florence by another group from Orofino, and at almost the same time placers were found at New-some, Dixie, and along the Salmon River. By 1872 the richest placers were depleted, and the Chinese took over most of the workings. After 1900, low-grade placers were worked at several localities, but it was not until the 1930's that a real revival of the placers was made possible by higher prices, development of new mining equipment, and improved transportation facilities (Lorain and Metzger, 1938, p. 6-8, Thomson and Ballard, 1924, p. 13-14).
Gold-bearing veins were worked as early as 1866 in the Warren district (Ross, 1941, p. 62), but the important lode mines at Elk City, Dixie, and Buffalo Hump were developed in the 1880's and 1890's. After a few years of intense activity, lode mining declined in Idaho County and reached a low in 1920 (Lorain, 1938, p. 7). Activity increased in the 1930's because of higher prices and improved transportation, but a general decline in both lode and placer activity was again dominant from 1950 through 1959.
Total gold production before 1904 was estimated at from $35 to $55 million by Lindgren (1900, p. 233, 238; 1904, p. 84) and at $47 million by Thomson and Ballard (1924, p. 13). Production from 1905 through 1936 was 101,354 ounces of placer and 122,008 ounces of lode gold (Lorain and Metzger, 1938, p. 9). From 1905 through 1959 a total of 455,554 ounces of gold was produced in Idaho County. Staley (1946, p. 20, 21) presented yearly production data from 1862 through 1942 that totaled 2,176,550 ounces.
In general the oldest rocks in Idaho County are gneisses, schists, quartzites, and limestones of the Belt Series of Precambrian age (Shenon and Reed, 1934, p. 10). These were intruded by the Idaho batholith, a granodiorite and quartz monzonite body that underlies much of central Idaho and most of Idaho County. Unconformably overlying these rocks at low altitudes are remnants of the Columbia River Basalt, basaltic lavas which were poured out on a mature erosion surface during Tertiary time.
Gold-bearing fissure veins occur in both the metasedi-mentary rocks of the Belt Series and in the granitic rocks of the Idaho batholith near intrusive contacts (Shenon and Reed, 1934, p. 24).
BUFFALO HUMP DISTRICT
The Buffalo Hump district is between lat 45°30' and 45°40' N. and long 115°35' and 115°45' W., in the west-central part of Idaho County.
Gold was discovered in this remote district in 1898 at the Big Buffalo property which developed into its chief producer. The rush to this new area was more frantic than to most areas and the lawlessness and excesses, for which it became known, were perhaps intensified by its remoteness and primitiveness.
Several towns were built, and despite almost impassable roads, machinery was brought in and mining flourished (Thomson and Ballard, 1924, p. 98, 103). But metallurgical problems, high costs, relatively small deposits, and transportation problems were obstacles too large to overcome, and the boom collapsed after a few years. Except for small-scale operations, the mines have been idle for many years.
According to Shenon and Reed (1934, p. 4) and Ross (1941, p. 52), the Buffalo Hump district produced ore valued at about $700,000, most of which was in gold, with undetermined amounts of silver and copper. From 1939 through 1941 the district produced 2,307 ounces of gold, but no activity has been reported since that time. Total gold production through 1959 was about 27,000 ounces.
The bedrock in the district consists of quartzite and schist of the Belt Series and quartz monzonite of the Idaho batholith. The metasedimentary rocks were folded into a northwest-trending overturned anticline and then invaded by the quartz monzonite. The veins, about 20 in all, occupy an area 5 miles long and .5 to 1.75 miles wide in a shear zone along the crest of the anticline (Shenon and Reed, 1934, p. 26).
Individual veins usually are less than half a mile long and terminate by horsetailing and splitting into thin stringers. Pyrite, tetrahedrite, sphalerite, chalcpoyrite, galena, and native gold are the common ore minerals of the veins. Small amounts of arsenopyrite, stibnite, molybdenite, and tellurides may be present, and quartz is the dominant gangue mineral (Shenon and Reed, 1934, p. 27).
In the Dixie district, which is in Tps. 25 and 26 N., R. 8 E., about 20 miles south of Elk City, gold placers were discovered in 1861 and were extensively and successfully mined during the early years. Lode deposits were developed in 1891 (Thomson and Ballard, 1924, p. 73), but their exploitation was hampered by the remoteness of the area. There has been very little activity in the district in recent years.
Production data for this district are incomplete. Lorain and Metzger (1938, p. 50) noted that $270,500 (13,000 ounces) worth of placer gold was shipped from the district from 1861 to 1863 and that the total production of the placers was probably less than $1 million (48,500 ounces). Thomson and Ballard (1924, p. 13), however, estimated $1.5 million (72,800 ounces) in gold as the production of the district.
Lode mines, according to Ross (1941, p. 55), produced gold worth about $50,000 (2,400 ounces). Total production for the district through 1959 was approximately 40,000 to 75,000 ounces.
The geology of the Dixie district is similar to that of the Elk City district. Quartz monzonite or granodiorite of the Idaho batholith is the dominant rock. Numerous inclusions of the older country rock - schist, gneiss, and quartzite - are incorporated in the igneous intrusion and are exposed locally (Thomson and Ballard, 1924, p. 73). The ore deposits are in quartz veins containing pyrite and gold.
ELK CITY DISTRICT
The Elk City district is in parts of Tps. 29 and 30 N., R. 8 E., near Elk City.
The first gold discovery in Idaho County was at Elk City in 1861. Here rich placers attracted 2,000 people the first year, but by 1872 the best ground was worked out, and the Chinese took over the operations. In 1870 gold-quartz veins were found at the Buster property, but very little gold was mined until 1902.
The Buster mine became the largest lode producer in the district and produced about $300,000 in gold between 1907 and 1909 (Lorain, 1938, p. 28). The mines produced fairly steadily from the early 1900's through the 1930's, but since World War II they have been inactive. Placers, on the other hand, were active through 1957.
The early gold production of the district was estimated at $5 to $10 million by Lindgren (1904, p. 84) and at $18% million by Thomson and Ballard (1924, p. 13). From 1902 to 1939 the lodes produced more than $725,000 in gold (Ross, 1941, p. 55) from 1933 to 1959 lodes and placers produced 75,575 ounces. Total production, including the early estimates, was about 550,000 to 800,000 ounces.
Bedrock in the Elk City district consists of granite gneiss, a kind of gneissic shell formed along the contact of the Idaho batholith with metasedimentary rocks of the Belt Series (Thomson and Ballard, 1924, p. 22-23, 60). Small patches of the quartz monzonite of the batholith are exposed at various localities near Elk City, and Tertiary sediments underlie the valley at Elk City.
The veins are quartz lenses as much as 20 feet thick and 300 feet long. They are arranged in a radial pattern in the gneiss, near the quartz monzonite contact (Shenon and Reed, 1934, p. 24-26), and most of them trend at right angles to the foliation in the gneiss. The ore minerals of the veins are native gold, pyrite, tetrahedrite, sphalerite, chalcopyrite, and galena.
The placers of the district are in so-called high-level gravels of Tertiary age (Reed, 1934, p. 8-16).
FRENCH CREEK-FLORENCE DISTRICT
The French Creek-Florence district is in T. 25 N., Rs. 3 and 4 E., about 42 miles from Grangeville, the nearest supply point.
In the 1860's this area was one of the most productive in the State; the gulches and stream beds swarmed with miners working the rich gravels. The gravels were only 4 to 10 feet thick, and the richer parts soon were exhausted, after which the Chinese took over and reworked the tailings. The total output of the district, most of which was produced in the 1860's, was valued between $15 and $30 million (Lindgren, 1900, p. 233).
By the 1880's, production had dropped to between $30,000 and $45,000 worth of gold per year (Lindgren, 1900, p. 233). A few small lode properties were developed in later years but the district has been deserted for a long time except for a brief revival in the late 1930's. Total production through 1959 was about 1 million ounces; nearly all production was from the early placers.
Bedrock in the district consists of soft, decomposed quartz monzonite which is cut by numerous small, but rich, gold-quartz veins (Lorain and Metz-ger, 1938, p. 47). These veins were the source of the gold in the stream gravels.
The Orogrande district is in T. 27 N., R. 7 E., about 12 miles southwest of Elk City.
Lode mines were developed in the late 1890's; however, the largest mines, the Orogrande-Frisco and the Gnome, were not productive until 1902 and 1932 respectively (Shenon and Reed, 1934, p. 52). The Gnome produced 11,582 ounces of gold from 1932 to 1937, when it was closed (Lorain, 1938, p. 44). The district produced small quantities of gold annually through 1957 and through 1959 its total was 32,000 ounces; almost all production was from lodes.
Country rock in the Orogrande district consists of quartz monzonite and granodiorite of the Idaho batholith and schist of the Belt Series (Shenon and Reed, 1934, p. 30, 31, pi. 1). The ore deposits are of two types: gold-pyrite disseminated through a silicified shear zone in the schist, and small veins and stringers of quartz and sulfides in granodiorite and dacite. The dacite intruded the granodiorite and the mineralization is related to the dacite. Ore minerals consist of pyrite, chalcopyrite, galena, tet-radymite, molybdenite, native gold, gold telluride, wolframite, and scheelite.
SIMPSON-CAMP HOWARD-RIGGINS DISTRICT
The Simpson-Camp Howard-Riggins placer district, in Tps. 24 to 28 N., R. 1 E., along the Salmon River between Riggins and Freedom, has been intermittently productive since the 1860's. Most of the activity immediately followed the initial discoveries; from 1862 to 1866 an estimated $575,000 in gold was produced (S. M. Barton, M. W. Wells, and E. Oberllig, written commun., 1958).
In the 1930's, large-scale but unsuccessful mining methods were introduced (Lorain and Metzger, 1938, p. 80). The district, which was still active in 1959, produced a total of 9,578 ounces of gold from 1903 through 1959.
The placer deposits are in bench and stream gravels. The bench gravels, which have been more productive (Lorain and Metzger, 1938, p. 82-85), occur along the main stream canyon as much as several hundred feet above present stream level. The stream gravels consist of small bars along the present river course.
The Tenmile district is between lat 45°33' and 45°55' N. and long 115°31' and 115°44' W., immediately north of the Buffalo Hump district and west of the Elk City district.
Both placer and lode deposits were worked in this district, but the placers were more productive. Gold was discovered in 1861 in Newsome basin in the gravels of Newsome Creek. Most of the gravels were soon exhausted, but they yielded approximately $2 million (about 100,000 ounces) in gold (Ross, 1941, p. 61).
Lode properties were developed as early as 1888 (Lorain, 1938, p. 30), and they emerged in recent years as the more important sources of gold. The lode mines produced an estimated minimum of 18,400 ounces of gold to about 1932 (Shenon and Reed, 1934, p. 71-82). From 1932 through 1959 the district produced 28,671 ounces. Total estimated gold production was about 147,000 ounces.
Bedrock in the area consists of gneiss and quart-zite of the Belt Series and granodiorite and quartz monzonite of the Idaho batholith. The granitic rocks intrude the gneiss. The ore deposits are in quartz veins that fill fractures and faults in gneiss, quartz monzonite, and quartzite. Variable amounts of the sulfides, pyrite, chalcopyrite, arsenopyrite, chalcocite, galena, covellite, and sphalerite occur in the veins, and gold is associated with the sulfides (Shenon and Reed, 1934, p. 71-82).
The Warren-Marshall (Resort) district is in southern Idaho County between Tps. 20 and 24 N., and Rs. 4 and 8 E.
Rich placers were discovered in Warren Meadows in 1862 shortly after the discoveries at Florence; rich lode deposits were found as early as 1866 (Lindgren, 1900, p. 238-239). Before 1900 an estimated $15 million in gold was mined from the district; most of it, from placers. After the initial boom period which lasted through the 1860's, activity continued on a much-reduced scale, especially from 1902 to 1932 (Reed, 1937, p. 25).
Bucket dredges were introduced in 1932, and large-scale placer production recreated on a lesser scale the booming days of the 1860's. Production from placers gradually diminished through the 1950's.
Detailed production data for the district from 1902 through 1936 were listed by Reed (1937, p. 25). From 1902 through 1928, the combined output of lodes and placers was 21,581 ounces of gold. From 1929 through 1935, lode mines yielded $37,992 (about 1,765 ounces) and placers $1,593,062 (about 56,640 ounces). From 1936 through 1959 the district produced 98,519 ounces. Total gold production, including Lindgren's estimate of early production, was about 906,500 ounces.
The oldest rocks in the Warren-Marshall district are quartzite, gneiss, and schist of the Belt Series of Precambrian age. These rocks are intruded by quartz monzonite of the Idaho batholith, the predominant bedrock in the district (Reed, 1937, p. 8) ; over most of the district, the quartz monzonite is deeply weathered. Locally, lamprophyre dikes of middle Miocene age also intrude the older rocks.
The gold lodes are known collectively as the Warren vein system, consisting of quartz veins in a strong set of northeast-trending joints in the quartz monzonite. Mineralization probably occurred in Late Cretaceous time before the intrusion of the lamprophyre dikes. The primary vein minerals are gold, galena, sphalerite, tetrahedrite, stibnite, and pyrite in a gangue composed mainly of quartz and locally abundant calcite and muscovite. Arsenopyrite, ruby silver, chalcopyrite, and scheelite may be found at some localities, and silver is rare (Reed, 1937, p. 35-37).
The most productive placers in the district occur in unconsolidated deposits called younger gravels by Reed (1937, p. 13-15) and in Recent alluvium. These are distinguished from older gravels which are believed to be middle Miocene to Wisconsin in age (Reed, 1937, p. 12). The younger gravels include bench gravels and high meadow deposits; the Recent alluvium consists of broad sand and gravel deposits along present streams. The older gravels have been mined locally but have sustained no large production.