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Hollandite with Manganite

#PD39254

Hollandite with Manganite

#PD39254
Availability
Sold
Size
5 x 7 x 3.5 cm - Sm Cabinet 
Formula
BaMn2+Mn4+7O16 (RRUFF)
Locality
Marshall, Albany Co., Wyoming, United States

Crusts of submicroscopic Hollandite with minute, 1mm, prismatic crystals of Manganite on Quartz and Calcite matrix. The label with the mineral states that the small prismatic crystals are Hollandite after Manganite. This is possible, but I can't say without EDS. Pyrolusite may be the shiny black crusts.

Hollandite

Formula
BaMn2+Mn4+7O16 
Crystal System
Monoclinic 
Crystal Habit
Striated, Prismatic, Acicular 
Cleavage
Good, None, None 
Luster
Earthy (Dull) 
Color
grayish black, black, silver gray 
Streak
black 
Class
Monoclinic - Prismatic 
Fracture
Brittle 
Hardness
4-6 

Data courtesy of Webmineral.

Collection
Phillips Collection

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