Molybdenite in mica matrix (probably from the Carnaíba Mining District, Bahia, Brazil) 1 : 無料・フリー素材/写真
Molybdenite in mica matrix (probably from the Carnaíba Mining District, Bahia, Brazil) 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 | 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 6100 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 sulfide minerals contain one or more sulfide anions (S-2). The sulfides are usually considered together with the arsenide minerals, the sulfarsenide minerals, and the telluride minerals. Many sulfides are economically significant, as they occur commonly in ores. The metals that combine with S-2 are mainly Fe, Cu, Ni, Ag, etc. Most sulfides have a metallic luster, are moderately soft, and are noticeably heavy for their size. These minerals will not form in the presence of free oxygen. Under an oxygen-rich atmosphere, sulfide minerals tend to chemically weather to various oxide and hydroxide minerals.Molybdenite is a molybdenum sulfide mineral (MoS2). It has hexagonal crystals, metallic luster, a bright silvery color, and a dark gray streak. It is fairly soft (H=2) and has one cleavage plane. Molybdenite is especially distinctive in being flexible - thin scales or plates of molybdenite will easily bend but won't snap back into shape as biotite or muscovite mica do.Molybdenite is nearly identical to graphite (C) in its physical characteristics (see: www.flickr.com/photos/jsjgeology/sets/72157650963514503). Graphite is a principally a metamorphic mineral. Molybdenite is usually an igneous mineral, occurring in hydrothermal veins and pegmatites. It also occurs in some contact metamorphic rocks (skarns - www.flickr.com/photos/jsjgeology/sets/72157646562268189).The specimen seen here consists of a silvery mass of molybdenite in a matrix of dark mica. The rock is probably from Brazil's Carnaíba Mining District, where emerald, quartz, and molybdenite occur in a "biotite schist" matrix called "sludite". The mica in sludite rock in this area is reportedly between biotite and phlogopite in composition.Locality: unrecorded / undisclosed (but probably from the Carnaíba Mining District, ~west of the town of Pindobaçu, Bahia State, eastern Brazil) |
| 撮影日 | 2024-07-25 15:10:53 |
| 撮影者 | James St. John |
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