Formula: K(Cr,Ti,Fe,Mg)12O19
Origin of name: from locality Yimeng Mountain, Shandong Province, China
Crystal system: Hexagonal
Crystal class: 6/m 2/m 2/m
Twinning:
Unit cell: a = 5.875, c = 22.94
Colour: Black
Diaphaneity: Opaque
Luster: Metallic
Habit: Platy to tabular grains, irregular, to 0.5 to 2 mm, as reaction rims surrounding host mineral
Hardness: 4
Specific gravity: 4.34
Cleavage: 2; {0001} perfect, {1120} good, {10-11} sometimes present
Tenacity:
Streak: Brown
Synonyms/varieties:
Comments:
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