Formula: Mn9(Si, Al)10O24(OH)8
Origin of name: Locality; Akatore Creek, Otago, New Zealand
Crystal system: Triclinic
Crystal class: -1
Twinning: on {0-21}; twin axis perpendicular {0-21}, lamellar in thin section
Unit cell: a = 8.337 Å, b = 10.367 Å, c = 7.629 Å, a = 104.46°, b = 93.81°, g = 104.18°
Colour: Yellow-orange to orange-brown
Diaphaneity: Transparent
Habit: Crystals prismatic, elongated and striated parallel to a-axis; massive to radiating
Hardness: 6
Specific gravity: 3.48
Cleavage: 2; {010} excellent; {0-12} imperfect
Streak: Yellow white
Synonyms/varieties:
Comments: Found in manganiferous metachert and carbonate lenses in schists, also in manganiferous potassium-rich felsic metavolcanics
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