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Proto-ferro-anthophyllite

Year of discovery: 1998 (Japan)

Locality list: 4 localities of proto-ferro-anthophyllite

• Fe₇Si₈O₂₂(OH)₂
• (Fe,Mn)₂(Fe,Mg)₅Si₈O₂₂(OH)₂
• [][Fe²⁺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: Grunerite (Monoclinic), Ferro-anthophyllite (Orthorhombic)

• Fe => Mg: Anthophyllite, Cummingtonite, Proto-anthophyllite

• Fe₂ => Mn₂: Clino-ferro-suenoite, Proto-ferro-suenoite
• Fe₂ => Ca₂: Ferro-actinolite
• Fe₂ => Na₂: Riebeckite

• Color: Pale yellowish brown
• Streak: White
• Luster: Vitreous
• Diaphaneity: Transparent

• Habit: Acicular, Prismatic

• Cleavage: Perfect on {210} (2 planes, 120 degree)
• Density: 3.6

• System: Orthorhombic
• Group: mmm, Pnmn
• Lattice: a=9.4, b=18.4, c=5.3