Mineralpedia Details for Bementite

Named for American mineral collector Clarence Sweet Bement. It is an uncommon but widespread mineral that occurs in the United States, England, Sweden, Russia, Japan, and South Africa among several others. Bementite can be found in layers parallel to veins of calcite and intergrown with other manganese minerals. Associated minerals include calcite, willemite, hausmanntie, jacobsite, braunite, alleghanyite, baryte, grossular, johannsenite, rhodochrosite, and inesite.

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

Formula

Mn₇Si₆O₁₅(OH)₈ 

Crystal System

Monoclinic 

Crystal Habit

Massive, Radial 

Cleavage

Perfect, Good, Good 

Luster

Vitreous (Glassy) 

Color

brown, gray, yellow, yellow brown, pink 

Streak

yellow white 

Class

Monoclinic - Prismatic 

Hardness

6 

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Light pink, thin platy crystals to 0.5mm in open vugs and composing the matrix.