Swaknoite

swaknoite

mundrabillaite

dittmarite

arcanite

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Formula: (NH4)2Ca(PO3OH)2.H2O
Hydrated acid phosphate, orthorhombic paramorph of monoclinic mundrabillaite
Crystal System: Orthorhombic
Specific gravity: 1.91 measured, 1.89 calculated
Hardness: 1½ to 2
Colour: White
Solubility: Soluble in water
Environments

Cave deposits

Although swaknoite was approved in 1991, to date (October 2022) it has been reported only from the type locality.

Localities

At the type locality, the Arnhem Cave, Windhoek Rural, Khomas Region, Namibia, swaknoite occurs as a white coating on the dolomite walls of the cave, associated with mundrabillaite, forming shiny prisms up to 5 mm long, with dittmarite forming a microcrystalline chalky material, and with arcanite forming plates, up to 1 cm across, displaying a micacious texture. Swaknoite derives from the decay of bat guano which produces NH3 and H3PO4 that react with the cave walls containing Ca (Bulletin of the South African Speleological Association 32.72-74).

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