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Mangano-grunerite

Year of discovery: 1855 (Dannemora mine, Sweden), 1938 (Japan)

Locality list: 54 localities of mangano-grunerite

• Mn₂Fe₅Si₈O₂₂(OH)₂
• [][Mn²⁺₂][Fe²⁺₅][(OH)₂|(Si₄O₁₁)₂]^14-

• Class: Mg-Fe-Mn amphibole subgroup < w(OH,F,Cl)-dominant amphibole group < Amphibole supergroup
• Class: Inosilicate (Double chain) - Hydroxide

• Polymorph: Proto-ferro-suenoite (Orthorhombic)

• Mn => Fe: Grunerite, Ferro-anthophyllite, Proto-ferro-anthophyllite
• Mn => Ca: Ferro-actinolite
• Mn => Na: Riebeckite

• Fe => Mg: Mangano-cummingtonite (Series)

• Color: Brown, Yellowish green, Dark green
• Streak: White
• Luster: Vitreous
• Diaphaneity: Translucent-Opaque

• Habit: Acicular, Prismatic

• Cleavage: Perfect on {110} (2 planes, 120 degree)
• Hardness: 5-6
• Density: 3.3

• System: Monoclinic
• Group: 2/m, C2/m
• Lattice: a=9.6, b=18.0, c=5.3, β=104.3

Synonym: Dannemorite