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Formula: CuAl4(AsO4)2(OH)8(H2O)4
Hydrated arsenate
Crystal System: Monoclinic
Specific gravity: 2.70 to 2.803 measured, 2.734 calculated
Hardness: 5 to 6
Colour: Turquoise-blue
Solubility: Insoluble in water, but soluble in hydrochloric and nitric acids, and in KOH
Environments
Ceruleite occurs in the oxidised zone of arsenic-rich polymetallic
mineral deposits; a post-mine product
(HOM).
Localities
At an unknown locality in southern Bolivia ceruleite consists of deep blue concretions up to 10 across, seen
under the
electron microscope to consist of rod-like crystals up to 5 microns long and 2 microns thick. Associated minerals
include quartz, baryte,
goethite and mansfieldite
(AM 62.598-599).
At the type locality, the Emma Luisa Mine, Guanaco Project, Taltal, Antofagasta Province, Antofagasta, Chile,
ceruleite occurs in the oxidised zone of the arsenic-rich polymetallic
mineral deposit. Associated minerals include
pharmacoalumite,
olivenite, schlossmacherite,
mansfieldite and quartz
(HOM).
At the Cap Garonne Mine, Le Pradet, Toulon, Var, Provence-Alpes-Côte d'Azur, France, ceruleite is associated
with malachite, azurite,
olivenite, mansfieldite and
pharmacosiderite
(HOM).
Ceruleite from Cap Garonne - Image
At Wheal Maid, St Day, Gwennap, Cornwall, England, UK, ceruleite is associated with
posnjakite, scorodite,
metazeunerite, cassiterite,
tourmaline and quartz
(HOM).
Ceruleite from Wheal Maid - Image
At Wheal Gorland, St Day, Cornwall, England, UK, ceruleite occurs as sky-blue botryoidal aggregates and spheres,
1 to 1.5 mm in diameter, occurring on liroconite and associated with
clinoclase and olivenite or
chrysocolla
(AM 40.933).
Ceruleite from Wheal Gorland - Image
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