Rhodonite (English spelling)

Japanese: ロードナイト（英語表記）rhodonite

A mineral with the chemical composition (Mn,Fe2 ⁺ ,Ca) _SiO3 . It is also called rhodonite. It belongs to the triclinic crystal system, has a specific gravity of 3.57-3.76, a Mohs hardness of 5.5-6.5, and perfect cleavage at {110} and {10}. It is a transparent crystal with a pink to red to reddish brown color. Euhedral crystals are rare, and it is mostly found in clumps. It crystallizes in manganese replacement deposits and in veins caused by hydrothermal activity. It belongs to the pyroxene group, has a single-chain structure consisting of five _SiO4 tetrahedrons, and although Mn is the main component as an octahedral ion, it always contains Ca ions. However, Ca/(Ca+Mn) never exceeds 0.2.

Source: Heibonsha World Encyclopedia, 2nd Edition Information

Japanese:

化学組成(Mn,Fe^2＋，Ca)SiO₃の鉱物。バラ輝石ともいう。三斜晶系に属し，比重3.57～3.76，モース硬度5.5～6.5，へき開は｛110｝，｛10｝に完全。桃～赤～赤褐色の透明結晶。自形結晶はまれで多くは塊状で産する。マンガン交代鉱床や熱水作用による鉱脈中に晶出する。準輝石族に属しSiO₄四面体が5個からなる単鎖構造で，八面体イオンとしてMnが主成分であるが，必ずCaイオンを含む。しかしCa/(Ca＋Mn)は0.2を超えることはない。

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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