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Formula: Fe3+4Ti3As3+O13(OH)
Arsenite, titanium-bearing
mineral
Crystal System: Monoclinic
Specific gravity: 4.56 calculated
Hardness: 5½
Streak: Black
Colour: Black
Environments
Metamorphic environments
Hydrothermal environments
Localities
At the Monte Arsiccio Mine, Sant'Anna di Stazzema, Stazzema, Lucca Province, Tuscany, Italy, graeserite occurs
as prismatic to tabular black crystals, usually twinned, in carbonate veins, where it is
vanadium-rich, or as porphyroblasts in
schist, where it is
vanadium-poor. Along with minor
chromium, vanadium replaces
iron and titanium.
Arsenic is dominant over antimony
and detectable amounts of barium and lead
have been measured
(MM 84.5.766-777)
Associated minerals include ankerite,
arsenopyrite, baryte,
bianchiniite, dolomite,
galena, hyalophane,
pyrite, quartz,
rutile, siderite,
sphalerite, stibivanite and
tourmaline
(HOM).
Graeserite from the Monte Arsiccio Mine -
Image
At the type locality, Gorb, Lärchultini, Binn, Goms, Valais, Switzerland, graeserite was discovered 1995 in
hydrothermal veins that occur in a two-mica
paragneiss, or in small cavities in proximity to such veins. Numerous
specimens have been found at the locality, accompanied by a wide range of other hydrothermal minerals, including
anatase, arsenopyrite,
asbecasite, bournonite,
cafarsite,
cervandonite-(Ce),
chernovite, fetiasite,
gold (traces), hematite,
magnetite, monazite-(Ce),
rutile and tennantite.
(CM 36.1083–1088).
Graeserite from Gorb - Image
At the Passaic pit, Sterling Hill, Ogdensburg, Sussex County, New Jersey, USA, graeserite occurs in
metamorphosed Precambrian calc-silicate gneissic rock in the footwall
of a zinc - iron -
manganese orebody
(Mindat).
Graeserite from the Passaic Pit -
Image
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