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Formula: Ba(Mn4+6Mn3+2)O16
Multiple oxide, coronadite group,
manganese-bearing mineral
Specific gravity: 4.95
Hardness: 6
Streak: Black
Colour: Slivery grey to black
Common impurities: Fe,Pb,K,Na
Environments:
Metamorphic environments
Hydrothermal environments
Hollandite is a primary mineral in
contact metamorphic manganese ores,
and a secondary weathering product of
earlier manganese-bearing minerals, associated with
bixbyite-(Mn),
braunite, piemontite and
other manganese oxides
(HOM).
Localities
At Ilfeld, Harz mountains, Germany, hollandite occurs rarely in fissures in massive
manganite ores, or encrusting
baryte
(Minrec 41.6.493).
At Kajlidongri, Jhabua state, India, hollandite occurs in quartz
veins traversing a manganese orebody
(Dana).
At Nuba Mountain, Kordofan Province, Sudan, hollandite occurs intergrown with
pyrolusite
(Dana).
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