Mineralpedia Details for Orthopinakiolite

Named as an orthorhombic (ortho) mineral and its relationship to pinakiolite. Orthopinakiolite is a rare mineral found only at its type locality at Långban in Sweden where it occurs “in veinlets in granular dolomite in a metamorphosed Fe-Mn orebody.” Orthopinakiolite occurs in association with hausmannite, manganophyllite, dolomite, and calcite.

Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/orthopinakiolite.pdf

Formula

Mg₂Mn³⁺O₂(BO₃) 

Crystal System

Orthorhombic 

Cleavage

Good, None, None 

Luster

Metallic 

Color

black 

Streak

brown gray 

Class

Orthorhombic - Dipyramidal 

Fracture

Brittle 

Hardness

6 

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Long black, prismatic, striated crystals to 1cm.