Calcite-lined geode (Vinton Member, Logan Formation, Lower Mississippian; Mohawk Dam spillway, western Coshocton County, Ohio, USA) 2 : 無料・フリー素材/写真
Calcite-lined geode (Vinton Member, Logan Formation, Lower Mississippian; Mohawk Dam spillway, western Coshocton County, Ohio, 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 | Calcite-lined geode from Ohio, USA. (field of view ~6.8 cm across)A mineral is a naturally-occurring, solid, inorganic, crystalline substance having a fairly definite chemical composition and having fairly definite physical properties. At its simplest, a mineral is a naturally-occurring solid chemical. Currently, there are over 5400 named and described minerals - about 200 of them are common and about 20 of them are very common. Mineral classification is based on anion chemistry. Major categories of minerals are: elements, sulfides, oxides, halides, carbonates, sulfates, phosphates, and silicates.The carbonate minerals all contain one or more carbonate (CO3-2) anions.Calcite is a common mineral. It is calcium carbonate (CaCO3). It has a nonmetallic luster, commonly clearish to whitish to yellowish to grayish in color, is moderately soft (H≡3), moderately light-weight, has hexagonal crystals, and rhombohedral cleavage (three cleavage planes at 75º & 105º angles - cleavage pieces look like lopsided boxes). The easiest way to identify calcite is to drop acid on it - it easily bubbles (effervesces) in acid. The bubbles are carbon dioxide gas. If the acid is dilute hydrochloric acid, the chemical reaction is: 2HCl(aq) + CaCO3(s) -->> CO2(g)↑ + H2O(l) + CaCl2(aq) The most important & voluminous calcitic rocks in the world are limestone (sedimentary), marble (metamorphic), carbonatite (igneous), and travertine (speleothem, or "cave formations", and many hotspring deposits). Quite a few hydrothermal veins in the world are calcitic or have calcite as a principal component.The sample shown above is an irregularly shaped cavity ("geode") lined with calcite.Host rock: Vinton Member, upper Logan Formation, Osagean Stage, upper Lower MississippianLocality: Mohawk Dam emergency spillway, northwest of the town of Nellie, western Coshocton County, eastern Ohio, USA (vicinity of 40º 21' 26.42" North latitude, 82º 04' 57.97" West longitude)---------------------Photo gallery of calcite:www.mindat.org/gallery.php?min=859 |
| 撮影日 | 2016-04-18 18:03:39 |
| 撮影者 | James St. John |
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