Oriental Mine (Alta Mine), 16 to 1 Mine (Sixteen-to-One Mine; Original Sixteen-to-One Mine), Alleghany, Alleghany Mining District (Forest Mining District), Sierra County, California, USAi

Regional Level Types
Oriental Mine (Alta Mine)	Mine
16 to 1 Mine (Sixteen-to-One Mine; Original Sixteen-to-One Mine)	Mine
Alleghany	- not defined -
Alleghany Mining District (Forest Mining District)	Mining District
Sierra County	County
California	State
USA	Country

A former lode Au-Ag-Pt occurrence/mine located in sec. 4, T18N, R10E, and in sec. 33, T19N, R10E, MDM, about 2 km (1.2 miles) SW of Alleghany, along the N canyon wall of Kanake Creek, on private (patented) land within a National Forest area. Discovered and first produced in 1865. Owned/operated by the Dickey Exploration Company (100%), California (1974). MRDS database stated accuracy for this location is 100 meters. The property is an intermittent producer. There was activity at the mine in 1977. Water, electrical power and roads exist at the site for the sole purpose of mining operations, but are inadequate for a larger operation.

Mineralization is a vein Au deposit (Mineral occurrence model information: Model code: 273; USGS model code: 36a; Deposit model name: Low-sulfide Au-quartz vein; Mark3 model number: 27), hosted in quartzite. The ore body strikes N77W and dips 39N at a thickness of 3 meters and a depth-to-top (depth-to-bottom ??) of 305 meters, width of 610 meters and a length of 385 meters. Ore body No. 1 is tabular in a shear zone. Ore body No.2 is massive in a fissure vein. Ore body No. 3 is an irregular replacement body. The primary mode of origin was hydrothermal and the secondary mode was contact metasomatism. Primary ore control was faulting and the secondary control was igneous activity. Wallrock alteration is moderate (propylitic & silicification). Local alteration includes carbonitization and albitic alteration. The oldest rock is schistose quartzite, which grades into fine-grained mica schist with thin quartzite bands. Quartzite is not found in underground workings. Local rocks include Mesozoic gabbroic rocks, unit 2 (undivided).

The vein was productive wherever serpentine contact was explored. The most productive area was a narrow band of gabbro between granite and serpentine. A new ore body was discovered in 1952. Veins consist of branches and stringers with the greatest thickness on the 7th and 8th levels. The vein displaces a porous granite dike about 160 feet horizontally and 200 feet down dip. The dike is 50 feet thick in the upper workings and 350 feet thick in the lower workings.. The granite is coarse, up to ICM+. The feldspar in gabbro is unrecognizable and the augite is almost completely altered to hornblende. Minor thrusting occurred during and after mineralization. The Alta workings are 500 feet SSE of the Oriental shaft. Dumps there contain coarsely crystalline arsenopyrite and pyrite. Veins at the 2 mines may unite in broken ground above the 5th level.

Workings include surface and underground openings with a length of 4,847 meters and an overall depth of 237.74 meters and comprised of a 4,150 foot adit and raise that intersects an inclined shaft on the vein. There are 10 levels with short drifting on each. The Alta workings are caved.

Production data are found in: Ferguson, Henry G. & R.W. Gannett (1932) & Averill, Charles V. (1942a).

Detailed production statistics year by year are provided in USGS MRDS file #10116707.

Ore ran as high as $1000/ton (period values). Pt was detected in native Au samples up to 86.4 parts per million, averaging 32 parts per million. Reportedly $734,000 (period values) of Au was obtained from area on a vein 14 by 22 feet (?).

Other Databases

Link to USGS MRDS:	10086500

Other Regions, Features and Areas containing this locality

References