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Formula: MgAl(SO4)2Cl.14H2O
Hydrated sulphate, aubertite group
Crystal System: Triclinic
Specific gravity: 1.80 measured, 1.78 calcuated
Hardness: 2 to 3
Streak: White
Colour: Sky blue
Solubility: Soluble in water but not hygroscopic
Environments
Localities
At the type locality, Faraglione Ranni, Faraglioni di Levante, Porto Levante, Vulcano Island, Lipari, Eolie
Islands, Metropolitan City of Messina, Sicily, Italy, magnesioaubertite occurs as polycrystalline aggregates,
always enclosed by pickeringite, on a base of
alunogen in the Grotta de Faraglione. The aggregates are up to 2 cm in size
and consist of xenomorphic (being an irregular shape impressed by adjacent minerals) granular single crystals several
hundred micrometers across. Magnesioaubertite is transparent and has a sky-blue colour resembling that of
chalcanthite, white streak, glassy lustre and one good cleavage.
Magnesioaubertite is a rare secondary mineral formed by
the reaction of volcanic gases and aluminum-bearing rocks. Associated
minerals include alunogen,
pickeringite,
metasideronatrite,
native sulphur, tamarugite,
aluminocopiapite and
metavoltine
(AM 75.1433, HOM).
Magnesioaubertite from Faraglione Ranni -
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