Ferber Mining District, Elko County, Nevada, USAi

Regional Level Types
Ferber Mining District	Mining District
Elko County	County
Nevada	State
USA	Country

Per NOTES ON SOME MINING DISTRICTS IN EASTERN NEVADA BY JAMES M. HILL (1916):

"Location of mines. The Ferber district is in some low foothills 3 miles east of the main Toano Range in the extreme southeast corner of Elko County, 15 miles north of Ibapah, Utah. (See PL I.) The most eastern prospects of the district are about 2 miles west of the main freight road from Wendover, on the Western Pacific Railway, to Ibapah, and are close to the State line. Most of the prospects in the district are in a low, narrow east-west pass through the ridge and are within an area about 2 miles long by a mile wide. Beginning at the east, the properties on the north side of the pass are the Knowlton, Red Cloud, Big Chief, Martha Washington, and Ajax. The Salt Lake group lies on the south side of the pass opposite the Big Chief. The Regent mine is about 2 miles west of the Martha Washington, across the head of a broad, shallow valley which drains north. A 15-foot well in the bottom of Ferber Wash, about three-fourths of a mile east of the Knowlton property, furnishes all the water used, but, without question, water could also be obtained from shallow wells in Deep Creek Canyon opposite the mouth of Ferber Wash, where there is a small seep at which stock waters.

Geology. The low pass is cut in a small stock of quartz monzonite that weathers more rapidly than the surrounding limestones. The unmetamorphosed limestones are blue-gray and are distinctly bedded in 1 to 2 foot layers. No fossils were found in them, but their lithology and their position on the eastern flank of the Toano Kange suggest that they are of Carboniferous age. In general the beds strike east of north and dip southeast, but the structure near the mines is complicated and was not studied in detail.
The intrusive rock shows a rather wide range of texture, varying from a fairly coarse porphyritic quartz monzonite to a fine equigranular and somewhat gneissic rock that approaches granite. The normal porphyritic quartz monzonite has phenocrysts of andesine, quartz, and orthoclase (named in the order of decreasing abundance) in a fine granular intergrowth of orthoclase, quartz, and andesine. Biotite and hornblende occur both as phenocrystic minerals and in the groundmass. In some specimens 50 per cent of the rock consists of phenocrysts, but the proportions vary from place to place. The usual edge phase of this rock is finer grained and is more porphyritic than that from the center of the stock. At the Big Chief mine the rock is a fine equigranular aggregate of quartz orthoclase, andesine, and brown biotite. Gneissic banding has been developed to a slight extent near the north edge of the stock, but all gradations between the normal phase of quartz monzonite porphyry and the fine equigranular rock were noted.
The Regent mine is near the south contact of a small body of pyroxene-andesine rock (gabbro) that contains a small amount of interstitial quartz. In general it is a light-gray rock of fine granular texture, but in a few places it is of porphyritic texture. When examined in thin section under the microscope, it is seen to consist of gray-green augite and andesine with some orthoclase and a small amount of quartz. A dike of similar rock was noted about 50 feet west of the Martha Washington ore zone, cutting white crystalline limestone. This gabbro is possibly a differentiate of the quartz monzonite magma, though its relations to that rock are not definitely known.

Ore deposits. The ore deposits of the Ferber district were discovered about 1880 by the Ferber brothers, who did a little work on the Big Chief vein and what is now the Salt Lake group. They did not hold their claims very long, and the properties were relocated about 1890. At present the largest property, consisting principally of the Martha Washington and Salt Lake groups, is owned by W. M. Bradley and associates, of Salt Lake. There are 15 patented claims in the district and a large number of locations. So far as could be learned the production from the district is quite small, consisting of less than 100 carloads of oxidized copper and lead ores which carry a little silver and gold.
The ore deposits, with the exception of the Regent and Big Chief, are typical contact-metamorphic deposits in crystalline limestone adjacent to the small stock of quartz monzonite. The contact alteration has resulted in the formation of lenslike masses of epidote, yellowish-brown garnet, calcite, amphibole, and quartz. The bodies of lime silicate are usually near the intrusive rocks, and are arranged in belts parallel to the contacts, which appear to dip away from the stock on all sides. The contact-metamorphic deposits are chiefly valuable for copper, which is found in the form of chrysocolla and copper pitch ore. Copper carbonate minerals are present in all amounts, but do not form a large part of the ore. In some of the deeper workings chalcopyrite was noted, and chalcocite was found in the workings of the Salt Lake group at a depth of 40 feet. It is probably also present in the other mines, though it was not seen by the writer. The Big Chief is a siliceous vein cutting quartz monzonite about 100 feet from its north contact. The surface ores are limonitic and contain lead carbonate and a minor amount of oxidized copper minerals.
The Regent ore body is a shear zone that strikes east and dips south in a basic phase of the quartz monzonite. The siliceous ore carries principally oxidized lead minerals and a small amount of copper carbonate at the surface. At a depth of 100 feet there is a streak of massive galena on the hanging wall.

The properties. The Sidong claims, located by G. W. and S. A. Knowlton in January, 1908, lie on both sides of Ferber Wash, about 2 miles west of Deep Creek canyon. The principal development is a 40-foot whim shaft with 50 feet of drifting at the bottom. A drift trending S. 70° E., 40 feet in length, has evidently been driven to undercut an older 30-foot incline shaft sunk on the ore zone about 75 feet southeast of the whim. The ore body forms along an open fissure that strikes N. 20° E. and dips 80° W. Copper silicate and black copper pitch ore with some black oxide are the most abundant copper ores, but some malachite and azurite are present. The whim shaft is sunk on the contact of altered limestone and a small body of medium-grained quartz monzonite. Amphibole, epidote, and skeleton crystals of pink garnet are found in the zone of intense alteration, which is irregular but not wide. In the east drift the intrusive contact is peculiar, showing irregular fragments of altered limestone in the fine-grained edge phase of the igneous rock through a belt 4 feet wide. Postintrusive movement along the fissures has brecciated this rock and permitted the entrance of the solutions which deposited the copper minerals. In replacing the rock the mineralized solutions show a marked preference for the limestone, replacing it with chrysocolla and some copper carbonate. The igneous rock is less extensively mineralized.
Several other belts of copper-bearing lime silicate rock appear in open cuts on adjoining claims, both north and south of the canyon.
The Red Cloud workings, on a small flat south of the road in Ferber Wash, about a mile west of the Sidong claims, consist of several shallow pits sunk in red iron-stained siliceous croppings. The limonitic ore body occurs in a zone of brecciated white crystalline limestone on the north side of a vertical fissure that trends N. 60° E. and above a fault that strikes N. 45° W. and dips 40° SW. A little copper stain is seen here and there in the red ore and a few small patches of yellow lead carbonate were noted.
The Big Chief vein, the original discovery in the district, is about three-fourths of a mile west of the Red Cloud workings. The vein is 2 to 8 feet wide and stands well above the level flat on the summit of the pass. It strikes east and is nearly vertical, cutting a fine-grained, somewhat gneissic quartz monzonite. The vein is parallel to and about 100 feet south of the north contact of the igneous stock. It consists of white and dark-gray sugary quartz that on the surface is stained with iron and manganese oxides. The quartz has been brecciated and the crevices filled with limonite and with some copper and lead carbonates which are said to carry about $14 a ton in silver and lead. The vein is opened by several pits and by three shafts, the deepest of which goes down about 75 feet. None of the shafts could be entered. No sulphides were noted on the dumps.
The Martha Washington ground is at the west end of the stock about half a mile west of the summit of the pass. The deepest shaft on this ground, north of the road, is 100 feet deep, with a 50-foot drift west at the bottom. The collar of the shaft is in white crystalline limestone, which shows some lime silicate minerals and is about 15 feet west of a 20-foot belt of gossan that consists of epidote, garnet, and quartz. The zone of lime silicates, which dips about 60° W., crosses the shaft 40 feet below the collar, and is cut along its east side by the drift on the 100-foot level. A few residual masses of chalcopyrite and bornite, surrounded by copper pitch ore, are found at the 100-foot level. Both the croppings and the 40-foot level show some copper carbonate and silicate. Most of the ore shipped from this claim, said to average 12 per cent copper, has been taken from a 50-foot incline about 400 feet south of the road, in the ore zone. At this place the mineralization seems to be stronger than it is farther north, and the belt of lime silicate rock with abundant limonite and copper carbonates and silicates is 6 to 10 feet wide. It strikes N. 10° W. and dips about 50° W.
The Ajax workings on what appears to be the southward continuation of the Martha Washington ore zone, consist of a shaft 150 feet deep and of about 400 feet of drifting on the 75-foot and 150-foot levels. Copper carbonate ores with lime silicate minerals and quartz have been found in a north-south belt that dips west at medium angles.
The Salt Lake group of eight patented claims and five locations is on the south side of the pass, opposite the Big Chief. The principal work on the Covellite claim is a 100-foot shaft, but there are a number of short tunnels, inclines, and shafts at other places along the main ore zone. The ore bodies occur in an east-west belt that dips south at low angles, in white crystalline limestone about 200 feet south of the quartz monzonite contact. Garnet, epidote, amphibole, and calcite are abundant contact-metamorphic products, and the copper ores are found in lens-shaped masses with the lime silicate minerals. At the surface copper carbonates and silicates are the chief metallic minerals. Copper pitch ore is also present. At a depth of 40 feet some chalcocite was noted in the oxidized copper ore, and it is said that native copper was found at this depth. A few grains of chalcopyrite were noted in the ore on the dumps, but the development is not deep enough to have reached unaltered sulphides.
The Regent mine, belonging to Leffler Palmer, of Ibapah, is west of the head of a north-draining open valley that lies between Toano Range and Ferber Mountain about 2 1/2 miles west of the summit of Ferber Pass. The main development is a 150-foot vertical shaft on the south side of a low ridge composed of gabbro or pyroxene diorite. The collar of the shaft is about 20 feet south of the vein, which cuts across the shaft at a depth of 70 feet, and is 30 feet south of the shaft at the 300-foot level. It is estimated that the vein will be 70 feet south of the shaft at the 150-foot level, which had not reached the vein at the time of visit. At the surface a zone of yellow and red-stained crushed gabbro 20 feet in width, exposed in the open cut, strikes N. 62° W. and dips 70° SW. It is said that the ore from the cut has a value of $15 a ton in lead and silver. Some of the lead is in the form of powdery cerusite, but plumbojarosite was also seen in the ore. At the 100-foot level there is a streak of partly oxidized galena on the hanging wall of the ore zone. The 3 feet of ore next the hanging wall is reported to be of better grade than the remainder of the vein."

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