Shale, chert, and minor amounts of quartzite, greenstone, and limestone (NVOs;0)

State	Nevada
Name	Shale, chert, and minor amounts of quartzite, greenstone, and limestone
Geologic age	Ordovician
Original map label	Os
Comments	Shale and siltstone in the Palmetto Formation have locally been metamorphosed to hornfels (Albers and Stewart, 1972). The Comus Formation is approximately 25% limestone, 40% dolomite, and 35% shale; it ranges from 3,000 to 5,450 feet thick but makes up only an incidental part of this unit (Willden, 1964). A small portion of the Palmetto Formation in Esmeralda County has been assigned to NVOsv (Albers and Stewart, 1972).
Primary rock type	chert
Secondary rock type	shale
Other rock types	limestone; quartzite; andesite; siltstone; sandstone; chemical; greenstone; dolostone (dolomite)
Lithologic constituents	Major Sedimentary > Clastic > Mudstone > Shale (Bed)Primarily black shale but also cherty and argilliceous. Sedimentary > Chemical > Chert (Bed) Minor Sedimentary > Carbonate > Limestone (Bed) Metamorphic > Quartzite Incidental Sedimentary > Carbonate > Dolostone (Bed)Limited to Comus Formation. Sedimentary > Clastic > Sandstone (Bed) Sedimentary > Clastic > Siltstone (Bed) Metamorphic > Greenstone (Greenschist) Igneous > Volcanic > Mafic-volcanic > Andesite (Pyroclastic, tuff) Igneous > Volcanic > Mafic-volcanic > Andesite (Flow)
Map references	Stewart, J.H., and Carlson, J.E., 1978, Geologic Map of Nevada: U.S. Geological Survey and Nevada Bureau of Mines and Geology, 1:500,000 (not part of any formal series, printed and distributed by the U.S. Geological Survey, G75163, reprinted, 1981, G81386).
Unit references	Stewart, J.H., and Carlson, J.E., 1978, Geologic Map of Nevada: U.S. Geological Survey and Nevada Bureau of Mines and Geology, 1:500,000 (not part of any formal series, printed and distributed by the U.S. Geological Survey, G75163, reprinted, 1981, G81386). Stewart, J. H., 1980, Geology of Nevada: A discussion to accompany the Geologic Map of Nevada: Nevada Bureau of Mines and Geology Special Publication 4. Stewart, J.H., and McKee, E.H., 1977, Geology, Pt. 1, in Geology and Mineral Deposits of Lander County, Nevada: Nevada Bureau of Mines and Geology Bulletin 88, p. 1-59, 3 pl. Willden, R., 1964, Geology and Mineral Deposits of Humboldt County, Nevada: Nevada Bureau of Mines and Geology Bulletin 59, 154 p., 3 pl. Coats, R.R., 1987, Geology of Elko County, Nevada: Nevada Bureau of Mines and Geology Bulletin 101, 112 p., 1 pl. Albers, J.P., and Stewart, J.H., 1972, Geology and Mineral Deposits of Esmeralda County, Nevada: Nevada Bureau of Mines and Geology, 80 p., 2 pl. Kleinhampl, F.J., and Ziony, J.I., 1985, Geology of Northern Nye County, Nevada: Nevada Bureau of Mines and Geology Bulletin 99A, 172 p., 2 pl.
Geographic coverage	Elko - Esmeralda - Eureka - Humboldt - Lander - Mineral - Nye