A Geoscience Digital Image Library
A Geoscience Digital Image Library
| Title | Thin section of quartz monzonite porphyry |
|---|---|
| Description | Quartz monzonite porphyry thin section in plain polarized light. The 3 essential felsic species occur in 2 sizes. The larger plagioclases are euhedral and zoned and are phenocrysts, in places glomerporphritic. A few large subhedral kaolinized orthoclase grains are prsent as are large quartz anhedra. These are set in a poorly defined groundmass of variable grained quartz, orhtoclase, plagioclase, biotite and hornblende. Of these, the mafics are subhedral, the plagioclase is euhedral, the others anhedral. The hornblende is more strongly altered than biotite and is variably colored in pale green, bluish green, and buff. It is replaced by chlorite and epidote. Acccessories are magnetite, apatite, sphene, and zircon. |
| Location | USA ▹ Colorado ▹ Chaffee. Near Garfield. |
| Photographer | Darla Sondrol. 2002-03-21. |
| Collection | Ward’s Collection of Classic North American Rocks #6. |
| Key words | monzonite, porphyry, Colorado |
| Tech details | 831 KB. Thin section. Nikon FDX-35. |
| GeoDIL number | 2516 |
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