Formula: Ca2Fe(Fe,Al)2(SiO4)(Si2O7)(OH)2 . H2O
Origin of name: For Julian Goldsmith, American geochemist
Crystal system: Monoclinic
Crystal class: 2/m
Twinning:
Unit cell:
Colour: Greenish-black
Diaphaneity:
Luster: Nearly submetallic
Habit: Crystals, flat prismatic to bladed, fan-shaped plumose groups, granular
Hardness: 4.5
Specific gravity: 3.60
Cleavage: 1; {100} good
Tenacity:
Streak: Greenish-olive with blue tinge
Synonyms/varieties:
Comments: Two distinct species with the extensions -(Fe2+) and -(Fe3+) indicating the predominant cation in the second position in the formula; series with pumpellyite
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