Johnson mine

Mica Mine in Avery county, North Carolina

Johnson mine

Principal periods worked 1880, 1928-30, WWII, 1957.
Workings 7 adits, stopes, prospect pits, in area 200 by 450.
Description of muscovite Ruby, clear, small
Production Moderate sheet, large scrap.
Shape Lenses
Size 0.5-8 T, 10-100 L.
Dip Gentle
Relation to wallrock Partly concordant
Wallrock Interlayered hornblende and biotite gneiss, biotite alteration
Extent of weathering Unweathered
Remarks Pl-P-Q-M pegmatite, medium grained; accessory garnet, apatite, allanite?, pyrrhotite.
Source of information USGS, Sterrett (1923, p. 181), OF, 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