Rhyolite (TXpCAry;0)

State	Texas
Name	Rhyolite
Geologic age	preCambrian-Proterozoic [Grenville]
Original map label	pCry
Comments	Franklin Mtns.: rhyolite is porphyritic, feldspar and quartz phenocrysts, widely spaced but well-defined layering, massive, dark red to black, rounded quartzite pebble near base, thickness 1,400 ft max. Pump Station Hills: rhyolite porphyry, phenocrysts of pink feldspar up to 1 cm across and clear, glassy quartz, aphanitic groundmass, massive, maroon to dark red; base covered. (from Geol. Atlas of Texas, Van Horn-El Paso Sheet, 1968)
Primary rock type	rhyolite
Secondary rock type	porphyry
Other rock types
Lithologic constituents	Major Igneous > Volcanic > Felsic-volcanic > Rhyolite (Stock or pipe)porphyritic, well-defined layering, massive, dk. red or black, rded qtzite pebbles near base, thickness 1.400 ft max.
Map references	Bureau of Economic Geology, 1992, Geologic Map of Texas: University of Texas at Austin, Virgil E. Barnes, project supervisor, Hartmann, B.M. and Scranton, D.F., cartography, scale 1:500,000
Unit references	Bureau of Economic Geology, 1968, Van Horn-El Paso Sheet, Geologic Atlas of Texas: Bureau of Economic Geology, The University of Texas at Austin, scale 1:250,000.
Geographic coverage	El Paso - Hudspeth