Caoxite

caoxite

whewellite

baryte

ophiolite

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Formula: Ca(C₂O₄).3H₂O
Oxalate
Crystal System: Triclinic
Specific gravity: 1.87 calculated
Hardness: 2 to 2½
Streak: White
Colour: Colourless
Luminescence: No observed fluorescence
Environments

Metamorphic environments
Hydrothermal environments

Caoxite was approved in 1996 but to date (April 2023) it has been reported only from the type locality

Localities

At the type locality, the Cerchiara mine, Borghetto di Vara, La Spezia Province, Liguria, Italy, caoxite occurs as spherulitic and isolated aggregates, up to 0.5 mm across, consisting of colourless, stocky, tabular crystals up to 100 microns in size.
The caoxite is associated with quartz, baryte, and an unidentified manganese oxide in open fractures, 0.5 mm wide (AM 83.185-189).
Caoxite is thought to be hydrothermal, and it occurs in veinlets cutting metamorphosed manganese–barium-rich cherts in an obducted ophiolite (HOM).
Caoxite transforms into whewellite. Results confirm that this transformation into whewellite occurs directly by dehydration and not via weddellite (MM 69.1.77–88).

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