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Formula: BaMg3(Si2Al2O10)(OH)2
Phyllosilicate (sheet silicate), brittle mica group,
barium-bearing mineral
Crystal System: Monoclinic
Specific gravity: 3.30 measured, 3.33 calculated
Hardness: 2½ to 3
Streak: Yellow-white
Colour: Yellow-brown to colourless
Common impurities: Ti,Fe,Ca,Na,F,H2O
Environments
Localities
At the Netra manganese project, Balaghat District, Jabalpur Division, Madhya Pradesh, India,
barium-bearing micas occur in pockets in
manganese oxide-rich rocks enclosed in metapelites. Indications are that
metamorphism occurred at about 650oC temperature and 6 kbar pressure.
Micas have developed in manganese oxide-rich rocks where the latter have been invaded
by late silicic pegmatite and carbonate veins. In these pockets,
the manganese oxide-rich rocks contain braunite,
hausmannite, bixbyite-(Mn),
barium-bearing mica,
K-feldspar, hematite,
calcite, dolomite and
quartz. Braunite is the most abundant
phase, and bixbyite-(Mn) is enclosed in braunite.
The micas are secondary in nature
and are pseudomorphs after carbonates and
K-feldspars. One of the micas approaches
closely synthetic end-member kinoshitalite, and there is a complete solid solution between the
phlogopite and kinoshitalite end-members
(AM 74.200-202).
At the type locality, the Noda-Tamagawa mine, Noda, Kunohe-gun, Iwate Prefecture, Japan, kinoshitalite is
found as small scales less than 1 mm across in
hausmannite-tephroite ore from the 12th
level; it is also found at the 6th level in association with celsian,
quartz, spessartine,
rhodonite, chalcopyrite and
pyrrhotite
(AM 60.486-487).
At the Semail Ophiolite, Oman, kinoshitalite was studied in a
granulite facies
manganese ore associated with calcium- and magnesium- bearing
tephroite, hausmannite,
calcite and manganese-bearing
clinochlore, and in a second assemblage together with
hausmannite, altered tephroite,
manganese-bearing diopside and
calcite. The metamorphic rocks occur enclosed in
peridotites and were metamorphosed during
ophiolite obduction (The overthrusting of oceanic crust onto the leading
edges of continental plates)
(AM 85.242-250).
At the Hutter Mine, James River-Roanoke River Mn-Fe-Ba Mining District, Pittsylvania county, Virginia, USA,
kinoshitalite has been found in a metamorphosed manganese-bearing
marble. The metamorphic grade is middle
amphibolite facies, pressure 400 MPa and temperature
575oC. The kinoshitalite occurs in a single layered hand sample containing both
skarn and marble layers.
Kinoshitalite is scarce and fine-grained in manganese-bearing
marble and coexists with
kutnohorite, manganese-bearing
calcite, fluorine-bearing alleghanyite,
fluorine-bearing sonolite, aluminium-bearinng
jacobsite and alabandite.
Kinoshitalite is both more abundant and coarser-grained in skarn, where it
coexists with kutnohorite, tephroite,
fluorine-bearing manganhumite,
spessartine, jacobsite and
manganese-bearing magnetite.
The two likeliest source minerals for the barium in kinoshitalite found here are
baryte and barytocalcite
(AM 88.40-747).
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