A Geoscience Digital Image Library
A Geoscience Digital Image Library
| Title | Trachyte porphyry, Near Cripple Creek, Teller County, Colorado |
|---|---|
| Description | This very fine grained, porphyritic rock, is a trachyte porphyry. It contains many phenocrysts of feldspar (mostly altered remnants of sanidine), mafic phenocrysts that were amphibole before alteration, and a matrix of plagioclase, orthoclase and minor quartz. Accessory minerals include apatite, titanite (sphene), pyroxene, pyrite and calcite. The specimen is 9 cm across. |
| Chronostratigraphy | Tertiary (Post-Oligocene) |
| Location | USA ▹ Colorado ▹ Teller. Near Cripple Creek. |
| Photographer | Joseph Hartman. 2001-02-14. |
| Collection | Ward’s Collection of Classic North American Rocks #16. |
| Key words | trachyte, porphyry, Cripple Creek, Colorado |
| Tech details | 777 KB. Hand specimen. Fujifilm FinePix S1Pro digital camera; 60mm AF Nikon micro lens. |
| GeoDIL number | 77 |
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