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Formula: Ca3TiAs6Be2Si2O20
Arsenite, titanium and
beryllium bearing mineral
Crystal System: Hexagonal
Specific gravity: 3.70
Hardness: 6½ to 7
Colour: Yellow, pale yellow
Environments
Localities
At the Monte Cervandone area, Devero Alp, Baceno, Verbano-Cusio-Ossola Province, Piedmont, Italy, asbecasite
was one of the first new arsenic species to be found, on the Wannigletscher
in 1963; it has since been found throughout the Cervandone area. Most good crystals are less than 1 cm in size, but
exceptional deep orange transparent crystals exceeding 2 cm have been found. The bright yellow colour of fresh,
transparent asbecasite crystals has often caused them to be mistaken for the more common Alpine species
titanite. Rare wulfenite from
Cervandone can also be mistaken for asbecasite. Weathered crystals tend to look whitish or greenish yellow and
to be cloudy, having lost their original translucency or transparency.
Asbecasite is typically associated with cafarsite and other
arsenic minerals, as well as with
chlorite, fluorite,
magnetite and quartz
(MinRec 56.3.297-299).
Asbecasite from the Monte Cervandone Area -
Image
At the type locality, the Wanni glacier - Scherbadung area, Binn, Goms, Valais, Switzerland, asbecasite occurs
on cleft faces in orthogneiss. Associated minerals include
magnetite, hematite,
titanite, apatite,
anatase, malachite,
azurite, tennantite and
molybdenite
(HOM).
Asbecasite from the Wanni Glacier - Image
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