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Formula: Ca3(TiFe2+)(SiO4)3
Valence: Ca3Ti4+Fe2+Si3O12
Nesosilicate (insular SiO4 groups), garnet group,
garnet supergroup,
titanium-bearing mineral
Crystal System: Isometric
Specific gravity: 3.75 measured, 3.80 calculated
Hardness: 7½
Streak: Grey
Colour: Black
Common impurities: Zr,Al,Mn,Mg
Environments
Localities
At the type locality, the Fuka mine, Fuka, Bitchū, Takahashi City, Okayama Prefecture, Japan,
skarns were formed on both sides of the quartz
monzonite dykes that penetrated
limestones. The skarns consist mainly
of gehlenite and spurrite. Some parts of the
skarns are altered to retrograde minerals such as
garnet, vesuvianite,
bicchulite, fukalite and others.
Contaminated rocks occur between the quartz
monzonite and skarns. The
contaminated rock was derived from a magma that intruded the limestone and
subseqently changed its composition during the formation of skarns. It usually
consists of pyroxene and feldspar and
sometimes contains various amounts of grossular,
vesuvianite and wollastonite.
Morimotoite occurs in the contaminated rock and is associated with clinopyroxene,
feldspar, vesuvianite,
andradite-grossular,
wollastonite and prehnite, and with small
amounts of perovskite, titanite,
apatite, biotite,
epidote, hematite,
zircon, baddeleyite and
calzirtite.
Morimotoite occurs as euhedral or subhedral grains up to 15 mm in size with or without rims of
andradite-grossular. The mineral is black in
colour with adamantine lustre. Cleavage is not observed
(MM 59.115-120).
Morimotoite from the Fuka Mine - Image
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