Birch mine

Mica Mine in Mitchell county, North Carolina, this site also known as Steven Green

Birch (Steven Greene) mine

Principal periods worked 1900, 1914-20, 1925, 1929, 1942-47, 1955-59.
Workings Incline and stope >500; several adits, shafts.
Description of muscovite Brownish green, clear, moderately ruled, bent, tied.
Production Large sheet, scrap.
Shape Irregular, tabular.
Size 1-25, T, >500 L
Strike NE
Dip SE
Plunge SW
Relation to wallrock Partly concordant
Wallrock Hornblende gneiss, biotite, alteration
Extent of weathering Partly weathered (100 ft)
Remarks Irregularly zoned: Pl-P-Q-M pegmatite, fine to coarse grained in upper workings; Pl pegmatite, coarse grained; accessory quartz, muscovite, garnet, in lower workings with Pl-M pegmatite along foot wall, center, or hanging wall; Q-Pl pegmatite, fine to medium grained, locally. Muscovite concentrated in the areas of low dip.
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