Fluorcalciomicrolite

fluorcalciomicrolite

tantalite-(Mn)

monazite-(Ce)

bityite

Images

Formula: (Ca,Na,☐)2Ta2O6F
Oxide, microlite group, pyrochlore supergroup, tantalum-bearing mineral
Crystal System: Isometric
Specific gravity: 6.160 calculated
Hardness: 4 to 5
Streak: White
Colour: Colourless
Luminescence: No fluorescence under UV
Common impurities: Na,Nb,OH
Environments

Pegmatites

Localities

At the type locality, the Volta Grande mine, Nazareno, Minas Gerais, Brazil, fluorcalciomicrolite occurs as an accessory mineral in the granitic pegmatite that is exceptionally enriched in lithium and rubidium. Associated minerals include microcline, albite, quartz, muscovite, spodumene, lepidolite, cassiterite, tantalite-(Mn), monazite-(Ce), fluorite, apatite, beryl, garnet, epidote, magnetite, gahnite, zircon, tourmaline, bityite, hydrokenomicrolite and other microlite-group minerals.
Fluorcalciomicrolite occurs as euhedral, untwinned, octahedral crystals 0.1 to 1.5 mm in size, occasionally modified by rhombododecahedral faces. The crystals are colourless and translucent with adamantine to resinous lustre. (MM 77.2989-2996).

Fluorcalciomicrolite from the Volta Grande Mine - Image

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