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Mineralpedia Details for Hollandite

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Hollandite

Hollandite

Named after Dr. Thomas Henry Holland, former Director of the Indian Geological Survey. An uncommon but widespread mineral found in localities in India, Sweden, Norway, Germany, Morocco, and the United States, and others. It can be found as a primary mineral in manganese ores that have been contact metamorphosed and as a secondary mineral as a weathering product of manganese bearing minerals.

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

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 
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Hollandite from Jakobsberg mine, Filipstad, Värmland, Sweden

Hollandite
            from Jakobsberg mine, Filipstad, Värmland, Sweden

Long prismatic black crystals to 7cm with metallic luster, black streak and hardness of about 6. 

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Hollandite from Deep Portland pit, Wharf mine, Lawrence Co., South Dakota, United States

Hollandite
            from Deep Portland pit, Wharf mine, Lawrence Co., South Dakota, United States

Shiny metallic acicular crystal sprays to 2mm in alkali trachyte porphyry.

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Hollandite from Ultevis, Lappland, Sweden

Hollandite
            from Ultevis, Lappland, Sweden

Hollandite is a basic Mn-oxide with barium in the structure. These are good sized crystals from any regard approaching over 5cm. Usually Hollandite occurs as tiny acicular crystals in sprays.

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Hollandite from Socorro, New Mexico, United States

Hollandite
            from Socorro, New Mexico, United States

Black, glittering fine acicular or fibrous carpet of Hollandite. 

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Hollandite from Walter Mayfield prospect, Jeff Davis Co., Texas, United Stastes

Hollandite
            from Walter Mayfield prospect, Jeff Davis Co., Texas, United Stastes

Dull black-grey mass of Hollandite.

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