Boltwoodite (Delta Mine, Emery County, Utah, USA) 1 : 無料・フリー素材/写真
Boltwoodite (Delta Mine, Emery County, Utah, USA) 1 / 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 | Boltwoodite from Utah, USA. (Robert Lauf collection)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 5500 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 silicates are the most abundant and chemically complex group of minerals. All silicates have silica as the basis for their chemistry. "Silica" refers to SiO2 chemistry. The fundamental molecular unit of silica is one small silicon atom surrounded by four large oxygen atoms in the shape of a triangular pyramid - this is the silica tetrahedron - SiO4. Each oxygen atom is shared by two silicon atoms, so only half of the four oxygens "belong" to each silicon. The resulting formula for silica is thus SiO2, not SiO4.Boltwoodite is a scarce hydrous potassium sodium uranyl hydroxy-silicate mineral, (K,Na)(UO2)(SiO3OH)·1.5H2O. It has a nonmetallic luster, a yellowish color, is about 3.5 to 4 on the Mohs Hardness Scale, usually forms earthy masses or radiating clusters of elongated crystals, and is radioactive. Boltwoodite is a secondary uranium mineral that forms by alteration of uraninite (or other primary U minerals) in an oxidizing environment. The original U+4 ions in uraninite get oxidized into U+6 and usually become incorporated into uranyl ions, (UO2)+2. In the presence of water and potassium and sodium and silica, boltwoodite can form.Shown above is an apparent quartzose pebbly sandstone (= brown) with earthy boltwoodite (= yellow). This comes from a uranium-vanadium mine in central Utah where mineralization is developed in siliciclastic sedimentary rocks of the Chinle Formation (Upper Triassic). Mineralization occurred during the Paleocene.Locality: Delta Mine, Emery County, central Utah, USA (see locality info. at: www.mindat.org/loc-4377.html)---------------Photo gallery of boltwoodite:www.mindat.org/gallery.php?min=716 |
| 撮影日 | 2016-04-30 13:48:34 |
| 撮影者 | James St. John |
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