Mineralpedia Details for Johannsenite

Johannsenite

Named for Professor Albert Johannsen, a petrologist at the University of Chicago in Illinois, USA. Johannsenite is an uncommon mineral that occurs in Mexico, the United States, Italy, Japan, and a number of other localities. It occurs in quartz or calcite veins that cut through rhyolite, as well as in manganese-bearing skarn and metasomatized limestone.

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

Formula

CaMn²⁺Si₂O₆ 

Crystal System

Monoclinic 

Crystal Habit

Acicular, Massive - Granular 

Cleavage

Good, None, None 

Luster

Vitreous (Glassy) 

Color

brown, brownish black, greenish, gray, gray green 

Streak

greenish gray 

Class

Monoclinic - Prismatic 

Fracture

Uneven 

Hardness

6 

WebMineral

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Mindat

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Olive green acicular crystals covering most all of matrix.