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Formula: Ca4Mg(AsO4)2(AsO3OH)2.4H2O
Hydrated acid arsenate
Crystal System: Monoclinic
Specific gravity: 3.09 measured, 3.153 calculated
Streak: White
Colour: Colourless, white, pale rose, pink
Solubility: Dissolves in 1:10 acids
Environments
Localities
At the type locality, the Ightem mine, Ightem, Agdz Cercle, Zagora Province, Drâa-Tafilalet Region, Morocco,
irhtemite is probably formed from the dehydration of
picropharmacolite. It occurs as radial spherules less than
1 mm across, white, or pale pink due to traces of cobalt, and also as aggregates of colourless acicular crystals to 8 mm.
Associated minerals include sainfeldite and
erythrite
(AM 59.209, Minrec 38.5.379)
Ophiolite is the main rock type at the Ightem mine, which hosts
47 different species of minerals (as of May 2023)
(Mindat).
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