Megacrystic Charnockite (VAYhg;0)

Megacrystic Charnockite

Porphyritic, foliated pyroxene-hornblende granite contains potassium feldspar megacrysts up to 4 cm across; hornblende and magnetite-ilmenite are the dominant ferromagnesian minerals; color index is about 15. Pyroxene is thoroughly uralitized; plagioclase contains abundant small epidote prisms. Adjacent to contacts with overlying Cambrian clastic rocks, charnockite grades into unakite; includes Vesuvius megaporphyry of Bartholomew and Lewis (1984).

State	Virginia
Name	Megacrystic Charnockite
Geologic age	Proterozoic Y
Lithologic constituents	Major Igneous > Plutonic > Charnockite
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	NGMDB product page for 34878
Counties	Nelson - Rockbridge

Megacrystic Charnockite

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.