Metaperidotite, Metapyroxenite, and Hornblende Metagabbro (VAYum;0)

State	Virginia
Name	Metaperidotite, Metapyroxenite, and Hornblende Metagabbro
Geologic age	Proterozoic Y
Original map label	Yum
Comments	Blue Ridge Basement Complex, Middle Proterozoic (Grenville-Age) Plutonic Rocks. From expanded explanation (ref. VA002): Metaperidotite, hornblende metagabbro, and metapyroxenite. Metaperidotite, greenish-black, dark-yellowish brown weathering, medium-grained, massive; consists of serpentine, amphibole, dark chlorite, and magnetite; serpentine replaces subhedral olivine; non-pleochroic amphibole occurs as single crystals, presumably pseudomorphic after subhedral to anhedral pyroxene; some amphibole occurs as large poikilitic crystals. Hornblende metagabbro, greenish-black, medium grained, speckled-white-weathering, massive, with a weak foliation and well-preserved primary igneous fabric; subhedral plagioclase is replaced by clinozoisite and albite; anhedral pyroxene is replaced by fibrous tremolite; brown hornblende occurs as subhedral single crystals. Metapyroxenite, dark-greenish-gray to greenish-black, light-greenish-gray weathering, medium-grained, weakly-foliated actinolite-rich rock contains lesser chlorite; amphibole is pseudomorphic after pyroxene.
Primary rock type	serpentinite
Secondary rock type	greenstone
Other rock types
Lithologic constituents	Major Metamorphic > Metaigneous > Metaintrusive > Metaultramafic > Metapyroxenite Metamorphic > Metaigneous > Metaintrusive > Metagabbro Metamorphic > Metaigneous > Metaintrusive > Metaultramafic > Metaperidotite
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	Loudoun