Four Hills Mine, Hawley Lake, Sierra City Mining District, Sierra County, California, USAi

Regional Level Types
Four Hills Mine	Mine
Hawley Lake	Lake
Sierra City Mining District	Mining District
Sierra County	County
California	State
USA	Country

A former lode Au-Pb-Cu mine located in the NE¼ sec. 10 & in secs 2, 9 & 11, T21N, R11E, MDM, 1.7 km (1.1 miles) N of Hawley Lake (coordinates of record), about 15 km NW of Bassetts and about 16 km (10 miles) NNW of Sierra City (about 10-12 miles NE of Downieville), on private land within a National Forest area. MRDS database stated accuracy for this location is 1,000 meters.

Mineralization is a vein 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 Late Permian mafic intrusive rock and mica schist. The ore body strikes E10N and dips 45SW at a thickness of 6.1 meters. Large bodies of quartz were formed by the intersection of veins. E stringers intersect with the main vein, which varies from 1 to 20 feet in thickness, and averages 4 to 5 feet in thickness. The vein strikes E on the N end and N on the S end. The vein was said to resemble the Plumas-Eureka. Most ore occurred in pockets or small, rich ore shoots. Pockets ranged from $1500 to $6000 (period values) near surface. Also, high-grade ore occurs where the vein comes in contact with mica schist and where veinlets leave the main vein and butt against, and are cut off by, mica schist. Local rocks include Paleozoic metavolcanic rocks, unit 2 (Northeastern Sierra Nevada).

Workings include surface and underground openings with an overall depth of 100.58 meters and comprised of a shaft, a 1,100 foot adit that intersects the shaft at 150 feet; also, surface and near surface pocket mines. 2 adits adjacent to the Four Hills are supposedly part of the Four Hills. The USGS mineral record card for the Sierra Iron Company also includes these adits on their property. A possible error exists here.

Production data are found in: MacBoyle, Errol (1920b).

Production occurred from Spanish times onward, intermittently. Totasl estimated yield was from $1,000,000 to $3,300,000 (period values). The early output was $1,000,000 to $1,500,000 (period values).

Other Databases

Link to USGS MRDS:	10086586

Other Regions, Features and Areas containing this locality

References