Formula: (Mg,Fe)5(SiO4)2(F,OH)2
Origin of name: From Greek for granule
Crystal system: Monoclinic
Crystal class: 2/m
Twinning: Common on {001}
Unit cell: a = 10.26 Ǻ, b = 4.73 Ǻ, c = 7.87 Ǻ, β = 109.0°
Colour: Yellow, brown, red
Diaphaneity:
Luster: Vitreous
Habit: Crystals varied, highly modified; massive
Hardness: 6 to 6.5
Specific gravity: 3.16 to 3.26
Cleavage: 1; {100} indistinct
Tenacity: Subconchoidal to uneven; brittle
Streak:
Synonyms/varieties:
Comments:
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