Pisolitic bauxite (Alcoa Bauxite Mine, Arkansas, USA) 2 : 無料・フリー素材/写真
Pisolitic bauxite (Alcoa Bauxite Mine, Arkansas, 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 | Pisolitic bauxite from Arkansas, USA. (~6.7 centimeters across at its widest)Bauxite is an aluminum oxide/hydroxide-rich rock. It is the richest source of aluminum compared with any other common rock, and is the best aluminum ore. Bauxites are mixtures of several Al-rich minerals, including gibbsite (Al(OH)3 - aluminum hydroxide), boehmite (gamma AlO·OH - aluminum hydroxy-oxide), and diaspore (alpha AlO·OH - aluminum hydroxy-oxide). They also tend to have clay minerals and iron oxide minerals. X-ray analysis is usually required to determine what specific minerals are present in any given bauxite sample. Many bauxites have pisolites, which are concentrically layered, spherical to subspherical structures. Aluminum is abundant in felsic and mafic igneous rocks (e.g., in the feldspars), but considerable heat and energy are required to get the aluminum metal out. Processing of bauxite requires much less heat and energy to produce Al metal. Despite that, an estimated 3% of America's electricity is used to produce aluminum from bauxite. Bauxite forms in tropical and subtropical environments, so most bauxite aluminum ores come from tropical countries. Bauxites are essentially fossil laterite soils - highly leached tropical soils. Strong chemical weathering in such areas leaches out many components of most bedrock lithologies, leaving behind aluminum hydroxy-oxides and some iron oxides.The sample seen here is a partial drill core of pisolitic bauxite from an Arkansas mine. Published analyses indicate that Arkansas bauxites are generally dominated by gibbsite, kaolinite (= a clay mineral, Al2Si2O5(OH)4 - aluminum hydroxy-silicate), and iron oxide minerals.Locality: Alcoa Bauxite Mine, east-southeast of the town of Bauxite, southeast-central Saline County, central Arkansas, USA---------------------------------------Info. on Arkansas bauxite:geology2.arkansas.gov/ags/Open%20File%20Reports/Aluminum/...--------------------------------Photo gallery of bauxite:www.mindat.org/gallery.php?min=575 |
| 撮影日 | 2025-03-03 12:34:45 |
| 撮影者 | James St. John |
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