Biotite Granite (VAYgbt;0)

State	Virginia
Name	Biotite Granite
Geologic age	Proterozoic Y
Original map label	Ygbt
Comments	Blue Ridge Basement Complex, Middle Proterozoic (Grenville-Age) Plutonic Rocks. From expanded explanation (ref. VA002): Biotite granite. Leucocratic, medium- to coarse grained, gneissic granite; dominantly perthitic Potassium feldspar, plagioclase, and quartz, with minor biotite, muscovite, and ilmenite; accessories include apatite and zircon. Feldspars show alteration to epidote and sericite; gneissic fabric is defined by flatten quartz and feldspars.
Primary rock type	granite
Secondary rock type
Other rock types
Lithologic constituents	Major Igneous > Plutonic > Granitic > Granite
Map references	Digital Representation of the 1993 Geologic Map of Virginia", 2003, CD ROM (ISO-9660) contains image file, expanded explanation in pdf, and ESRI shapefiles, viewing software not included. This is a digital version of "Geologic Map of Virginia" published in 1993. Available from: https://www.dmme.virginia.gov/commerce/ [https://www.dmme.virginia.gov/commerce/]
Unit references	Virginia Division of Mineral Resources, 1993, Geologic Map of Virginia: Virginia Division of Mineral Resources, scale 1:500,000 Digital Representation of the 1993 Geologic Map of Virginia - expanded explanation: 2003, Commonwealth of Virginia, Department of Mines, Minerals, and Energy, Divsion of Mineral Resources, Publication 147, 85 pp Digital Representation of the 1993 Geologic Map of Virginia", 2003, CD ROM (ISO-9660) contains image file, expanded explanation in pdf, and ESRI shapefiles, viewing software not included. This is a digital version of "Geologic Map of Virginia" published in 1993. Available from: https://www.dmme.virginia.gov/commerce/ [https://www.dmme.virginia.gov/commerce/]
Geographic coverage	Albemarle - Greene - Madison