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Formula: (Ce,Nd,La)(Fe3+,Ti,Fe2+,Al)3O2(Si2O7)1-x+y(AsO3)1+x-y(OH)3x-3y
Sorosilicate (Si2O7 groups), cerium-,
neodymium-, lanthanum-,
titanium- and arsenic- bearing
mineral
Crystal system: Trigonal
Specific gravity: 4.9 calculated
Hardness: 5
Streak: Brownish black
Colour: Black
Environments
Localities
There are two co-type localities, the Monte Cervandone area, Devero Alp, Baceno, Verbano-Cusio-Ossola Province,
Piedmont, Italy and the Wanni glacier - Scherbadung area, Binn, Goms, Valais, Switzerland.
At the type localities cervandonite-(Ce) forms small (typically less than 1 cm), lustrous rosettes of curved,
jet-black crystals, some with blue-green iridescent surfaces, commonly resting on
quartz or albite. It can be found
throughout the Binntal-Cervandone-Devero region. The largest specimens have come from around the Wannigletscher, with
aggregates exceeding 2 cm. It is typically associated with other arsenic
species characteristic of the area, including asbecasite,
cafarsite and
chernovite-(Y), and with
hematite, magnetite and
rutile. In the Lärcheltini Zone, cervandonite-(Ce) is sometimes
associated with graeserite
(MinRec 56.3.309-310).
Cervandoite-(Ce) from the Monte Cervandone Area -
Image
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