Powdermill mine

Mica Mine in Avery county, North Carolina, this site also known as Big, Shaft, McKinney

Powder Mill (Big, Shaft, McKinney) mine

Principal periods worked 1906, 1924, WWII, 1952.
Workings Cuts, inclines, shafts, stopes, 400 along strike, 100 deep.
Description of muscovite Greenish brown, hard, biotite, inter-growths, stained, bent, cracked.
Production Moderate sheet, feldspar.
Shape Branching, tabular.
Size 4-30 T
Strike E
Dip Steep S
Relation to wallrock Partly concordant
Wallrock Hornblende gneiss
Extent of weathering Weathered (35 ft).
Remarks Pl-Q-M-B wall zone, medium grained; accessory apatite, allanite. P-Pl-Q core, medium to coarse grained; accessory muscovite, biotite.
Source of information Sterrett (1923, p. 183), USGS, CMC, DMEA.

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