Viitaniemiite

viitaniemiite

eosphorite

morinite

montebrasite

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Formula: NaCaAl(PO4)F3
Anhydrous phosphate containing halogen
Crystal System: Monoclinic
Specific gravity: 3.245 measured, 3.242 calculated

Hardness: 5
Colour: Grey-white
Solubility: Readily dissolved by nitric and sulphuric acid
Environments

Plutonic igneous environments
Pegmatites
Carbonatites

Localities

At the Francon quarry, Montréal, Quebec, Canada, exceedingly rare viitaniemiite crystallised in the surfaces of vesicles in an alkalic silicocarbonatite, as delicate sprays and as solitary crystals up to 2 x0.5 x 0.2 mm in size. The vesicles are lined with crystals of colourless cryolite, calcite and yellow weloganite, and lesser amounts of viitaniemiite, pyrite, quartz, fluorite, dresserite, dawsonite, galena and sphalerite. Minute cubes of pyrite and fluorite have commonly grown on the viitaniemiite. In addition, cryolite has overgrown some viitaniemiite crystals near their points of attachment (CM 21.499-502). Viitaniemiite precedes cryolite, fluorite and pyrite in the paragenesis (Minrec 37.1.47). The Francon viitaniemiite is manganese-free (AM 69.961-966).

At the type locality, the Viitaniemi pegmatite, Eräjärvi area, Orivesi, Pirkanmaa, Finland, viitaniemiite occurs in the complex zoned granite
pegmatite as an inclusion in eosphorite and rimming morinite. It crystallised during hydrothermal replacement processes caused by residual fluids of the pegmatite melt. Associated minerals include fluorapatite, crandallite and montebrasite, as well as eosphorite and morinite (AM 66.1102, AM 69.961-966, HOM).

At the Greifenstein Rocks, Ehrenfriedersdorf, Erzgebirgskreis, Saxony, Germany, viitaniemiite occurs in druses in granite associated with lacroixite, morinite, apatite, childrenite, roscherite and tourmaline (HOM). It also occurs here associated with greifensteinite in a lithium-rich
pegmatite (CM 42.229).

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