One of the most basic uranium minerals. Ideal chemical composition: UO 2 . Usually further oxidized. Contains small amounts of radium, lead, helium, etc., which are products of the radioactive decay of uranium itself, and is highly radioactive. May contain thorium, cerium, yttrium, etc. as minor components. Colors include black, dark brown, greenish black, and steel gray. It is a cubic crystal system that forms idiomorphic crystals of regular hexahedrons and regular octahedrons, but is usually amorphous, often lumpy, granular, or soot-like. The cracks are irregular or shell-shaped. Submetallic to resinous luster. Source: Heibonsha World Encyclopedia, 2nd Edition Information |
最も基本的なウラン鉱物の一つ。理想化学組成UO2。通常はさらに酸化が進んでいる。ウラン自身の放射壊変の産物である少量のラジウム,鉛,ヘリウムなどを含み,強い放射能を持つ。副成分としてトリウム,セリウム,イットリウムなどを含むこともある。色は黒,黒褐,緑黒,鋼灰など。立方晶系で,正六面体,正八面体の自形結晶を作るが,普通は不定形で,塊状,粒状,すす状を呈することが多い。割れ口は不規則または貝殻状。亜金属~樹脂状光沢。
出典 株式会社平凡社世界大百科事典 第2版について 情報 |
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