Realgar & pararealgar & calcite on marble (Middle Eocene mineralization, 39 Ma; Getchell Mine, northern Osgood Mountains, northern Nevada, USA) 2 : 無料・フリー素材/写真
Realgar & pararealgar & calcite on marble (Middle Eocene mineralization, 39 Ma; Getchell Mine, northern Osgood Mountains, northern Nevada, USA) 2 / James St. John
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
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| 説明 | Realgar (red) and calcite (grayish-whitish) (field of view ~3.5 cm across)The whitish gray crystals are calcite (CaCO3 - calcium carbonate). The red crystals are realgar (AsS; aka As4S4 - arsenic sulfide). The small areas of yellowish and orangish are pararealgar, which has the same chemical formula as realgar. Realgar is unstable when exposed to light, so all the orangish-yellowish pararealgar you see in the rock used to be red realgar. Geology - Cambrian-aged Preble Formation limestone, contact metamorphosed into marble by the Cretaceous-aged Osgood Granodiorite Stock. During the late Middle Eocene, at 39 million years ago, the rock was subjected to Carlin-type mineralization by fluids moving along the Getchell Fault (a major normal fault formed during Basin & Range extensional tectonics). The mineralization event precipitated the calcite and the realgar (plus a teeny-tiny amount of disseminated gold, but not enough to make this sample a gold ore). Locality: 4950-194 stope of the Getchell Mine, northern end of the Osgood Mountains, eastern Humboldt County, northern Nevada, USA. |
| 撮影日 | 2014-09-02 21:56:33 |
| 撮影者 | James St. John |
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