A Geoscience Digital Image Library
A Geoscience Digital Image Library
| Title | Thin section of trachyte porphyry (bostonite) |
|---|---|
| Description | This is a photo of a plain polarized thin section of trachyte porphyry. Prominent phenocrysts are blocky to subrounded sodic orthoclse, turbid and zoned, with some being glomeroporphyritic. The matrix consists predominantly of equigranular tablets of zoned hematitic orthoclase, euhedral and in subparallel (trachytoid) arrangement. A few original mafic grains (pyrozene?) now consist of sericite, calcite, hematite, magnetite and sphene. Abundant accessory magnetite has been altered to hematite. Interstitial accessories are widespread: anhedral quartz, amall zircon euhdra, sericite flakes and grains of calcite. Veinlets of hematite cut the rock. |
| Chronostratigraphy | Post Ordovician |
| Location | USA ▹ New York ▹ Essex. Near Essex. |
| Photographer | Darla Sondrol. 2002-04-09. |
| Collection | Ward’s Collection of Classic North American Rocks #15. |
| Key words | trachyte, porphyry, bostonite, New York, thin section |
| Tech details | 419 KB. Thin section. Nikon FDX-35. |
| GeoDIL number | 2637 |
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