Formula: (Mn,Ca)Mn4O9.H2O
Origin of name: for Katsutoshi Takane (1899-1945), professor of mineralogy, Tohoku University, Sendai, Japan.
Crystal system: Hexagonal
Crystal class: unknown
Twinning:
Unit cell: a = 8.68, c = 9
Colour: Brownish gray, steel-gray to black
Diaphaneity: Opaque
Luster: Submetallic to dull
Habit: Massive, irregular nodules, colloform, banded, as inclusions in other minerals
Hardness: 2.5-3
Specific gravity: 3.41-3.43
Cleavage: None
Tenacity: Friable
Streak: Brownish black to dark brown
Synonyms/varieties: Wad
Comments: series with ranciéite
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