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Formula: BaCa6[(SiO4)(PO4)](PO4)2F
Nesosilicate, zadovite group,
arctite supergroup,
barium-bearing mineral
Crystal System: Trigonal
Specific gravity: 3.503 calculated
Hardness: 5 to 5½
Streak: White
Colour: Colourless
Luminescence: No fluorescence under UV
Environments
Localities
At the type locality, the Aradite type locality, Tamar Regional Council, Southern District, Israel,
pyrometamorphic rocks of
the Hatrurim Complex are highly unusual and formed as alteration products of a high-temperature combustion
process.
Grains of zadovite, together with aradite, occur only within
small veins of
schorlomite - rankinite
- pseudowollastonite -
gehlenite
paralavas in fine-grained
gehlenite
- larnite rocks. These minerals are generally confined to
coarse-grained
rankinite and often occur together.
There are three main types of occurrence of minerals of the
zadovite–aradite
series:
(1) grains up to 100–200 µm grown on apatite or enclosed by its
box-like crystals –
replacement of apatite by zadovite is also observed;
(2) xenomorphic grains 50–100 µm in size developed in the cracks of
rankinite and
gehlenite;
(3) small grains of zadovite–aradite not exceeding 10–15 µm in
size in
ellipsoidal aggregates of fine-grained barium-bearing minerals
(baryte, barioferrite,
gurimite, walstromite and
fresnoite), kalsilite and
wollastonite;
These are strongly altered to secondary calcium hydrosilicates.
Platy zadovite crystals with well-developed forms and xenomorphic crystals are observed.
Aradite and zadovite are associated with the rock-forming
minerals
gehlenite,
pseudowollastonite
and wollastonite, garnet
supergroup minerals of the andradite
– schorlomite
series, rankinite,
magnesioferrite,
kalsilite and
fluorapatite. Less
frequent associates are phosphorus-rich ellestadite,
larnite, cuspidine and
hematite.
The host rocks also display striking eutectic intergrowths of
schorlomite or gehlenite with a
larnite-like phase on the microscopic level. Accessory minerals are represented by
dorrite–khesinite,
barioferrite, walstromite,
baryte, gurimite,
fresnoite, delafossite,
cuprite, vorlanite,
perovskite and hexacelsian. The
mineral content of the fine-grained gehlenite host rocks mainly comprises
gehlenite, larnite,
magnesioferrite and andradite
(MM 79.1073-1087).
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