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Formula: Mn2+Ta2O6
One of the tantalite minerals. Multiple oxide,
columbite group, tantalum-bearing
mineral, forms series with tantalite-(Fe) and with
columbite-(Mn)
Crystal System: Orthorhombic
Specific gravity: 6.65 to 8 measured, 8.01 calculated
Hardness: 6 - 6½
Streak: brown
Colour: Black, brown
Solubility: Insoluble in hydrochloric and nitric acid; slightly soluble in sulphuric acid
Common impurities: Fe,Nb
Environments:
Tantalite-(Mn) occurs as an accessory and primary
constituent of granitic
pegmatites, and is detrital in placers. Associated minerals
include albite, microcline,
beryl, lepidolite,
muscovite, tourmaline,
spodumene, lithiophilite,
triphylite, amblygonite,
triplite, samarskite,
apatite, microlite and
cassiterite
(HOM).
Localities
At the Lipovsk pegmatite field, Rezhevsky District, Sverdlovsk Oblast, Russia, intergrowths of
tantalite-(Mg), tantalite-(Fe),
columbite-(Fe) and uranium-bearing
microlite form rims on
tantalite-(Mn)
crystals in andesine-calcite
nests in a deeply desilicated granite
pegmatite which crosscuts
serpentinite near its contact with
marble. Other associated minerals include
dravite-uvite,
chrysoberyl, phlogopite,
magnesio-hornblende to edenite,
cordierite, phenakite and
clinochlore
(Minrec 35.4.356-357).
The type locality is the Utö mines, Utö, Haninge, Stockholm County, Sweden.
At the Emmons pegmatite, Greenwood, Oxford county, Maine, USA, tantalite-(Mn) is common in the core-margin area,
and occurs in muscovite-rich pockets. It forms the inner portion of composite
wodginite/tantalite-(Mn) crystals. The Emmons
pegmatite is situated in
a belt of metasedimentary rocks which originated as marine sediments which were subsequently deformed and metamorphosed.
It is a highly evolved
boron-lithium-cesium-tantalum
enriched pegmatite
(R&M 94.6.516).
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