Gorceixite

gorceixite

dawsonite

alumohydrocalcite

nordstrandite

Images

Formula: BaAl3(PO4)(PO3OH)(OH)6
Hydrated phosphate containing hydroxyl, plumbogummite group, forms a series with goyazite
Specific gravity: 3.036 to 3.185
Hardness: 6
Streak: White
Colour: White, colourless, green or brown, may be mottled, colourless in transmitted light
Common impurities: Ca,Ce,Sr
Environments

Pegmatites
Carbonatites
Sedimentary environments
Hydrothermal environments

Gorceixite occurs in pegmatites, sedimentary phosphate beds, carbonatites, iron ore deposits, polymetallic veins and baryte-fluorite veins (Mindat). It is probably always a secondary mineral (HOM).

Localities

In the Sydney basin, New South Wales, Australia, gorceixite is associated with dawsonite, alumohydrocalcite and nordstrandite (HOM).

At the Moculta Phosphate Quarry, Angaston, Barossa Valley, North Mt Lofty Ranges, South Australia, gorceixite is rare and occurs as sprays to 2 cm across of pale grey to yellow crystals in cavities lined with crystals of fluorapatite. Some of the cavities also contain crystals of baryte to 1 cm (AJM 17.1.17).

At the type locality, Ouro Preto, Minas Gerais, Brazil, gorceixite occurs as rounded nodules in sediment (Mindat).

In the Bauru basin, approximately 2 km south of the town of Santo Iniicio, Paraná State, Brazil, Two fossil bone fragments were found in a sandstone outcrop. Gorceixite formed by the alteration of apatite was found in the fossil bones using X-ray powder diffraction, electron-microprobe analyses and optical microscopy. No convincing evidence was found to indicate a source of barium and strontium required for the replacement of calcium in the bone phosphate (CM 37.945-950).

At the Big Fish River, Dawson mining district, Yukon, Canada, gorceixite is associated with lazulite, siderite, limonite and quartz (HOM).

At the Benallt Mine, Rhiw, Aberdaron, Gwynedd, Wales, UK, gorceixite has been discovered on the mine dumps in association with fluorapatite and banalsite. It is secondary in formation, and probably post-mining in origin, formed by the alteration of fluorapatite and banalsite (M&M 33.59-60)

In Dale county, Alabama, USA, gorceixite has been found in four localities a few miles apart, three localities near Ariton and one near Dill. The gorceixite is found as irregular nodules up to several inches across, in weathered outcrops of marl (AM 43.688-694).

At the Ozark Mine, Silvermine, Fredericktown District, Madison county, Missouri, USA, gorceixite occurs in tin-tungsten deposits with fluorite, apatite and baryte (Dana).

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