Multiple oxide, cryptomelane group
Specific gravity: 4.95
Colour: Slivery grey to black
Common impurities: Fe,Pb,K,Na
Hollandite is a primary mineral in
contact metamorphic manganese ores,
and a secondary weathering product of
earlier manganese-bearing minerals, associated with
braunite, piemontite and
other manganese oxides
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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