- Usage in publication:
-
- Tincup quartz monzonite porphyry*
- Modifications:
-
- Named
- Dominant lithology:
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- Porphyry
- AAPG geologic province:
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- Piceance basin
Summary:
Named for stock west of Napoleon Pass in Tincup mining district, its type locality. Occurs as five separate bodies shaped in different forms (stock, sills, tongue) on northwest side of quad, Gunnison Co, in the Piceance basin. Varies in aspect depending on abundance of quartz as opposed to feldspar. Consists of phenocrysts of white feldspar, colorless to slightly smoky quartz and abundant hornblende in a greenish-gray to grayish-green aphanitic groundmass. About 60 percent of the feldspar phenocrysts are sodic andesine and others are orthoclase. Cut by veins related to Mount Princeton. Is older than Mount Princeton quartz monzonite. Thought to represent first stage of porphyry intrusion. Assigned a Paleocene?, Eocene?, and Oligocene? age.
Source: GNU records (USGS DDS-6; Denver GNULEX).
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
Asterisk (*) indicates published by U.S. Geological Survey authors.
"No current usage" (†) implies that a name has been abandoned or has fallen into disuse. Former usage and, if known, replacement name given in parentheses ( ).
Slash (/) indicates name conflicts with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). May be explained within brackets ([ ]).