Byard Benfield mine

Mica Mine in Avery county, North Carolina

Byard Benfield mine

Principal periods worked 1885-95, 1903, 1925, 1943-45, 1950's.
Workings Cut 200, stope, 150, stripped area 100 x 1 50.
Description of muscovite Greenish brown, cracked, mineral inclusions, biotite intergrowths, tied, bent, ruled.
Production Moderate sheet, large feldspar
Shape Irregular, lens.
Size 40 T
Strike NW
Dip SW
Relation to wallrock Discordant
Wallrock Mica gneiss
Extent of weathering Unweathered
Remarks Pl-P-Q-M wall zone, fine to medium grained; P-Pl-Q-M outer intermediate zone, medium to coarse grained; P-Q inner intermediate zone, medium to coarse grained; Q core; accessory biotite, garnet, pyrite, pyrrhotite, thulite.
Source of information USGS, OF

Geographic context


Principal periods worked
WWI World War I
WWII World War II
int intermittent
Small < 500 lb
Moderate 500-10,000 lb
Large > 10,000 lb
Size of pegmatite
D depth
L length
T thickness
avg average
Internal structure
B biotite
F feldspar
M muscovite
P perthite
Pl plagioclase
Q quartz
Source information
CMC Colonial Mica Corporation
DMEA Defense Minerals Exploration Administration
OME Office of Minerals Exploration
USGS U.S. Geological Survey
OF USGS open-file reports and maps