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Mineralpedia Details for Johannsenite

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Johannsenite

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
WebMineral
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Mindat
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Johannsenite from Iron Cap mine, Graham Co., Arizona, United States

Johannsenite
            from Iron Cap mine, Graham Co., Arizona, United States

Olive green acicular crystals covering most all of matrix.

Click thumbnail images for larger view.

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