Zadovite

zadovite

gehlenite

aradite

rankinite

Images

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

Metamorphic 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 zadovitearadite 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 zadovitearadite 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 andraditeschorlomite 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 dorritekhesinite, 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).

Back to Minerals