Formula: (Ca,K,Ba)2(V,V)8O20.6H2O
Origin of name: for John Straczek, American mining geologist
Crystal system: monoclinic
Crystal class: 2/m
Twinning:
Unit cell:
Colour: greenish-black, thin flakes are yellowish green
Diaphaneity: opaque
Luster: greasy
Habit: fibers to 0.5 mm, in fibrous foliated masses to 1 cm across, thin flakes
Hardness:
Specific gravity: 3.09 to 3.29
Cleavage: 1; {100} perfect
Tenacity:
Streak: greenish black
Synonyms/varieties:
Comments:
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