Corundum (Soutpansberg Range area, South Africa) 2 : 無料・フリー素材/写真
Corundum (Soutpansberg Range area, South Africa) 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 | 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 oxide minerals all contain one or more oxide anions (O-2). The oxide minerals include species that are hydroxy-oxides. The hydroxide minerals (those with one or more OH-) are usually considered together with the oxides. Many sulfide minerals are not stable in Earth-surface conditions. In the presence of oxygen and moisture, sulfide minerals tend to tarnish or alter to oxides and hydroxy-oxides. All except the most inert elements (such as the platinum-group elements and gold and noble gases) readily form oxides. Gold oxide forms only under special conditions.Corundum is aluminum oxide - Al2O3. At H≡9, it is the hardest common mineral, apart from diamond. Corundum forms hexagonal crystals, which is evident even in many river-worn specimens. The hexagonal columns of corundum typically have well-developed flat tops & bottoms. These flat ends are not cleavage planes - corundum has no cleavage. The cleavage-looking flat tops & bottoms of corundum are called partings (pseudocleavage). Additional breakages will not be along planar surfaces. Striations may be visible on the flat ends (click once or twice on the photo to zoom in on the specimen at right). The color of corundum is variable - it can be any color, including plaid patterns. If transparent and relatively fracture-free & inclusion-free, corundum is said to be of gem-quality, and the color determines the name of the gem.deep red = rubyblue = sapphirepale red = sapphirepale green = sapphirepurple = sapphireyellow = sapphireLocality: unrecorded / undisclosed site in the Soutpansberg Range area, Vhembe District, Limpopo Province, northeastern South Africa-------------Photo gallery of corundum:www.mindat.org/gallery.php?min=1136 |
| 撮影日 | 2022-04-20 10:14:32 |
| 撮影者 | James St. John |
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