Biotite-Muscovite Leucogranite Gneiss

Leucocratic, coarse- to very-coarse-grained granite gneiss contains subhedral to euhedral Potassium feldspar megacrysts, and interstitial quartz and plagioclase; muscovite, biotite, epidote, titanite, and magnetite-ilmenite make up 5 to 15 percent of the mode; hornblende and garnet are locally present. Plagioclase is largely replaced by felty masses of epidote, muscovite, and titanite; clusters of reen-brown, biotite laths contain subhedral to euhedral epidote prisms; magnetite-ilmenite is rimmed by anhedral masses of titanite. The rock contains a penetrative schistosty defined by biotite and muscovite.
State Virginia
Name Biotite-Muscovite Leucogranite Gneiss
Geologic age Proterozoic Y
Lithologic constituents
Major
Metamorphic > Gneiss > Biotite-gneissgranitic gneiss
Comments Blue Ridge Basement Complex, Middle Proterozoic (Grenville-Age) Plutonic Rocks
References

Virginia Division of Mineral Resources, 1993, Geologic Map of Virginia: Virginia Division of Mineral Resources, scale 1:500,000.

Virginia Division of Mineral Resources, 2003, Digital Representation of the 1993 Geologic Map of Virginia, Publication 174, CD ROM (ISO-9660) contains image file, expanded explanation in pdf, and ESRI shapefiles, scale 1:500,000.

NGMDB product
Counties Albemarle - Amherst - Nelson