Piedmontite (English spelling)

Japanese: 紅レン石(紅簾石) - こうれんせき（英語表記）piedmontite

A mineral with the chemical composition Ca ₂ (Al,Fe ³⁺ ,Mn ³⁺ ) ₃ Si ₃ O ₁₂ ･OH. It is a member of the epidote group, and is a species of monoclinic zoisite that contains 5% or more Mn ₂ O _3. It belongs to the monoclinic crystal system and has a columnar crystal shape elongated along the crystal axis b , but can also be granular or lumpy. It shows perfect cleavage on {001}. It is reddish brown to purple-red, and when observed in thin sections, it shows significant pleochroism from pink to violet. Mohs hardness is 6, specific gravity is 3.45 to 3.52. It occurs as a constituent mineral of pyrite schist in crystalline schist in the Nagatoro region of Saitama Prefecture and the southeastern part of Tokushima Prefecture, as well as in granite pegmatite and the host rock of manganese deposits.

Source: Heibonsha World Encyclopedia, 2nd Edition Information

Japanese:

化学成分Ca₂(Al,Fe^3＋，Mn^3＋)₃Si₃O₁₂･OHの鉱物。緑レン石族であって単斜ゾイサイト類のうちMn₂O₃を5％以上含有する種を呼ぶ。単斜晶系に属し，形態は結晶軸b軸方向に延びた柱状結晶を示すが，粒状，塊状となる場合もある。｛001｝に完全なへき開を示す。赤褐色～紫赤色であって，薄片で観察する場合ピンク～すみれ色の著しい多色性が見られる。モース硬度6，比重3.45～3.52。埼玉県長瀞（ながとろ）地方，徳島県南東部の結晶片岩中の紅レン石片岩の構成鉱物として産出するほか，花コウ岩ペグマタイト，マンガン鉱床の母岩中にも産出する。

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

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