Red Mountain Gneiss

Red Mountain Gneiss
State Texas
Name Red Mountain Gneiss
Geologic age preCambrian (Proterozoic)
Lithologic constituents
Major
Metamorphic > Gneissquartz-microcline-sodic plagioclase rock, pink. Varies widely from distinctly foliated and lineated fine-grained rock to a coarse granite; occurs as many, mostly concordant sills and lenticular bodies in southeast Llano region.
Minor
Igneous > Plutonic > Granitic > Alkali-feldspar-granite (Dome)
Incidental
Igneous > Plutonic > GraniticMetagranite in Cap Mountain area may be related to Red Mountain Gneiss
Comments Named for Red Mountain in southeast corner of Llano quadrangle, Llano County, Texas. Metagranite mapped on Cap Mtns. on the Llano 1:250,000 geologic quadrangle map may be related to Red Mountain Gneiss. Qtz-microcline-sodic plagioclase rock, pink; texture and grain size vary widely fr. a fine-grained rock with pronounced foliation and lineation to a coarse granite; occurs as many mostly concordant sills and lenticular bodies in SE part of Llano region
References

Paige, S., 1912a, Llano-Burnet, Texas: U.S. Geological Survey, Geologic Atlas of the United States, Folio 183.

https://pubs.er.usgs.gov/publication/gf183

Barnes, V.E., [1952?], Geologic map of the Blowout quadrangle, Blanco, Gillespie, and Llano Counties, Texas (1:31,680): University of Texas Bureau of Economic Geology.

Bureau of Economic Geology, 1981, Llano sheet, Geologic Atlas of Texas, Bureau of Economic Geology, University of Texas at Austin, scale 1:250,000.

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.

NGMDB product
Counties Blanco - Llano