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Formula: Mn3+O(OH)
Oxide containing hydroxyl
Specific gravity: 4.3 to 4.4
Hardness: 4
Colour: Brownish black to black
Solubility: Slightly soluble in hydrochloric acid; moderately soluble in sulphuric acid
Environments:
Pegmatites
Hydrothermal environments
Manganite is found associated with other manganese oxides in deposits formed by meteoric waters. It is often
found in
epithermal (low temperature) hydrothermal veins associated with
acanthite,
baryte,
cinnabar,
pyrolusite,
quartz,
siderite and
calcite.
It frequently alters to pyrolusite.
Localities
At and near Ilfeld, Harz mountains, Germany, manganite pseudomorphs
after calcite, and also hausmannite
pseudomorphs after manganite, have been found
(KL p146).
At Hartshill, Nuneaton, Warwickshire, England, UK, manganite occurs with manganoan
calcite
(RES p321).
At Laverock Braes, Middleton Park, Aberdeen City, Scotland, UK, manganite is the principal species of collector
interest, occurring as some of the finest specimens of manganite from the British Isles. Attractive crystal
sprays up to about 10 mm in length were found during recent rescue collecting at the site, where mining apparently
ceased in the early 20th century. Baryte,
kaolinite, pyrolusite,
quartz and paragonite? were also
identified. The principal iron oxide present is goethite. The minerals occur
as veins in granite, in coarse-grained
mica-rich metasediment and as loose masses in the overlying till
(JRS 22.11-28).
At the South Hecla mine, Calumet, Houghton county, Michigan, USA, tiny crystals of manganite have been found
associated with
quartz, epidote and
albite in voids in the conglomerate which hosts the mineralisation
(R&M 94.6.564).
At the Tamarack Jr. No. 1 mine, Calumet, Houghton county, Michigan, USA, tiny crystals of manganite have been
found in vugs
of crystallised albite
(R&M 94.6.564)
At the Central No. 2 mine, Keweenaw county, Michigan, USA, tiny crystals of manganite have been found in vugs in
crystallised
albite associated with epidote and
actinolite, and sometimes also with
hematite or
copper
(R&M 94.6.564, 97.4.358).
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