Chromitic metadunite (recrystallized) (Day Book Dunite; Green Mountain Mine, Yancey County, Blue Ridge, North Carolina, USA) 6 : 無料・フリー素材/写真
Chromitic metadunite (recrystallized) (Day Book Dunite; Green Mountain Mine, Yancey County, Blue Ridge, North Carolina, USA) 6 / 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 | Chromitic metadunite from North Carolina, USA.In orogenic belts, olivine-bearing rocks often have the olivine component altered and metamorphosed, usually into serpentine. North Carolina's Day Book Dunite is an exception to this. The unit is located in the Blue Ridge Province of the southern Appalachian Mountains. Dunites are 90%+ olivine varieties of peridotites, which are ultramafic intrusive igneous rocks. The Day Book Dunite appears to represent a metamorphosed sliver of mantle rocks, but it has not been serpentinized. In the rock seen here, the greenish material is forsterite olivine (magnesium-rich (Mg,Fe)2SiO4) - there are larger and smaller crystals. The black material is chromite (iron chromium oxide - FeCr2O4). Minor chlorite and magnesite are also present. The rock has been metamorphosed somewhat, and thus should really be called metadunite. The chlorite component is metamorphic in origin. Relatively large olivine crystals (up to 1 centimeter in size) show cleavage. The sand-sized olivine crystals have been attributed to metamorphic recrystallization, which took place during the Ordovician(?).The Day Book Dunite is mined - Unimin Corporation operates the Green Mountain Mine and produces olivine casting sand.Locality: Green Mountain Mine, ~2 kilometers southeast of the town of Day Book, northern Yancey County, Spruce Pine District, Blue Ridge, western North Carolina, southern Appalachians, USA (35° 58’ 02” North latitude, 82° 17’ 01” West longitude) |
| 撮影日 | 2021-01-20 23:37:51 |
| 撮影者 | James St. John |
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