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Iron meteorites are meteorites that consist overwhelmingly of an iron–nickel alloy known as meteoric iron that usually consists of two mineral phases: kamacite and taenite. Iron meteorites originate from planetary cores of planetesimals. The iron found in iron meteorites was one of the earliest sources of usable iron available to humans, before the development of smelting that signaled the beginning of the iron age. ==Occurrence== Although they are fairly rare compared to the stony meteorites, comprising only about 5.7% of witnessed falls, iron meteorites have historically been heavily over-represented in meteorite collections. This is due to several factors: * They are easily recognized as unusual even by laymen, as opposed to stony meteorites. Modern-day searches for meteorites in deserts and Antarctica yield a much more representative sample of meteorites overall. * They are much more resistant to weathering. * They are much more likely to survive atmospheric entry, and are more resistant to the resulting ablation. Hence, they are more likely to be found as large pieces. Because they are also denser than stony meteorites, iron meteorites also account for almost 90% of the mass of all known meteorites, about 500 tons.〔''The Universal Book of Astronomy: From the Andromeda Galaxy to the Zone of Avoidance'' by David Darling (2003), (p. 260 ).〕 All the largest known meteorites are of this type, including the largest—the Hoba meteorite. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「iron meteorite」の詳細全文を読む スポンサード リンク
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