Pigeonite (English spelling)

Japanese: ピジョン輝石 - ピジョンきせき（英語表記）pigeonite

A type of clinopyroxene that is poor in calcium. Its chemical composition is (Mg,Fe ²⁺ ,Ca)(Mg,Fe ²⁺ )Si ₂ O ₆ , with a Ca/(Mg+Fe+Ca) ratio of 0.5 to 0.15. Brown, greenish brown, or black short columnar to granular crystals. Monoclinic system. Mohs hardness 6. Specific gravity 3.17 to 3.46. The cleavage is prominent at {110}{10}, with the two intersecting at about 87 degrees. It often appears in the groundmass of relatively rapidly cooled igneous rocks such as tholeiitic andesite, basalt, and dacite, and rarely as phenocrysts.

Source: Heibonsha World Encyclopedia, 2nd Edition Information

Japanese:

Caに乏しい単斜輝石の一種。化学組成は(Mg,Fe^2＋，Ca)(Mg,Fe^2＋)Si₂O₆で，Ca/(Mg＋Fe＋Ca)が0.5～0.15の範囲のものを指す。褐色，緑褐色，黒色の短柱状～粒状結晶。単斜晶系。モース硬度6。比重3.17～3.46。へき開が｛110｝｛10｝に顕著で，両者は約87度で交わる。多くはソレアイト質系列の安山岩，玄武岩，デイサイトなど比較的急冷した火成岩の石基に，またまれに斑晶として出現する。

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

<<: Saint - Hijiri

>>: Beauty and the Beast - La Belle et la Bête