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Formula: Al4(PO4)3(OH)3
Anhydrous phosphate containing hydroxyl
Crystal System: Monoclinic
Specific gravity: 3.10
Hardness: 5½ to 6
Streak: White
Colour: Light green, colourless, bluish green. May be very blue because of mixtures with
scorzalite (Mindat)
Solubility: Virtually untouched by acids
Environments
Pegmatites
Metamorphic environments
Trolleite occurs in amphibolite-grade metamorphic rocks
(Webmin, HOM).
Localities
At the Rubindi pegmatite, Bwira, Ngororero District, Western Province, Rwanda, trolleite occurs with
ferrorosemaryite. The
ferrorosemaryite occurs as large grains reaching 3 mm, embedded in
scorzalite. Associated phosphate minerals inclue
scorzalite, trolleite,
montebrasite, bertossaite
and brazilianite, with accessory
augelite, triplite and
lacroixite
(EJM 17.5.749–759).
At the Buranga pegmatite, Gatumba, Ngororero, Western Province, Rwanda, trolleite is associated with
montebrasite, scorzalite,
bertossaite, brazilianite,
apatite, gatumbaite,
samuelsonite and wyllieite
(HOM)
At the type locality, the Västanå Iron Mine, Näsum, Bromölla, Skåne County, Sweden, trolleite is associated with
pyrophyllite, kyanite,
berlinite, attakolite,
augelite and lazulite
(HOM, Mindat)
At the Champion Mine, White Mountain Peak, White Mountains, Mono county, California, USA trolleite is associated with
scorzalite and augelite
(HOM, AM 59.974-984)
Alteration
augelite to trolleite, corundum and
H2O
3Al2(PO4)(OH)3 to Al4(PO4)3(OH)3 +
Al2O3 + 3H2O
(AM 64.1175-1183)
berlinite and H2O to trolleite and phosphoric acid
4Al(PO4) + 3H2O to Al4(PO4)3(OH)3 + H3PO4
(AM 64.1175-1183)
trolleite to augelite and berlinite
Al4(PO4)3(OH)3 to Al2(PO4)(OH)3 + 2Al(PO4)
(AM 64.1175-1183)
trolleite to berlinite, corundum and H2O
2Al4(PO4)3(OH)3 to 6Al(PO4) + Al2O3 + 3H2O
(AM 64.1175-1183)
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