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Tag Archives: Grunerite


Grunerite is an end member of the cummingtonite-grunerite series. Structure and composition are anal-ogous to cummingtonite. The name grunerite is by definition restricted to compositions close to end member Fe7Si8O22(OH)2.

  Hand Specimen identification: Habit, color, two prominent cleavages at 56° to each other, and association help identify grunerite, but it cannot be distinguished from other members of the cummingtonite series without chemical or X-ray analysis. Chemical Composition :Fe7Si8O22(OH)2 Hardness : 6 Specific Gravity3.1 to 3.6 Cleavage/Fracture : two perfect prismatic{110}/uneven …

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