Graeserite

graeserite

bianchiniite

stibivanite

cervandonite-(Ce)

Images

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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