- Usage in publication:
-
- White porphyry*
- Modifications:
-
- Overview
- AAPG geologic province:
-
- Eagle basin
Summary:
Is an intrusive sheet 1,500 ft thick of cream-white to light-gray porphyry with dendritic films of black manganese oxide that is generally free from alteration. Has a gray groundmass with scattered colorless phenocrysts of feldspar, quartz, and a few flakes of biotite. Lies above the Blue limestone. Also occurs as some dike-like masses. Is recognized from Carbonate and Iron Hills to Empire Gulch, the summits of Mount Sherman, Mount Sheridan, Peerless Mountain, and on the east slope of the Mosquito Range in the Leadville district, Lake Co, CO in the Eagle basin. Narrow sheets of the porphyry extend south and east from these areas. Principal vent may be at White Ridge southeast of Mount Sherman (Emmons) or at Breece Hill (Irving). Chemical analyses. Geologic maps. Of Late Cretaceous or early Tertiary age.
Source: GNU records (USGS DDS-6; Denver GNULEX).
- Usage in publication:
-
- White Porphyry*
- Modifications:
-
- Overview
- AAPG geologic province:
-
- Eagle basin
Summary:
Pando Porphyry of Late Cretaceous age includes rocks known as White Porphyry and as Mount Zion Porphyry [of the Gray Porphyry Group] in the Leadville district, Lake Co, CO in the Eagle basin. [Term White Porphyry not discussed.]
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 ([ ]).