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Phosphate

Goyazite

SrAl₃(PO₄)(PO₃OH)(OH)₆
Hardness4.5–5
Crystal systemHexagonal
ClassPhosphate
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Goyazite specimen

Goyazite Locality: Ilfeld , Nordhausen , Harz Mts, Thuringia , Germany ( Locality at mindat.org ) Picture width 0.4 mm. Collection and photograph Christian Rewitzer — Photo: Christian Rewitzer · CC BY-SA 3.0

Goyazite

Goyazite is an IMA-recognized mineral species in the phosphate class, with the chemical formula SrAl₃(PO₄)(PO₃OH)(OH)₆.

It crystallizes in the hexagonal crystal system (space group R-3m). It is a member of the Alunite-crandallite structural group.

Key properties: Mohs hardness 4.5–5; specific gravity 3.26; Greasy to resinous, pearly on cleavages luster; optically uniaxial.

IMA symbol Goy, IMA status: approved, named in 1884.

Found in granite pegmatites; from hydrothermal argillic alteration zones; in kaolinitic claystones derived from air-fall volcanic tuffs; in carbonatites; detrital.

It is found associated with Herderite, apatite, quartz (Alto Bernardino, Brazil); monazite, sphalerite, pyrite, barite, quartz (Wigu carbonatite, Tanzania); kaolinite (alteration zones).

The name refers to Goiás [Goyaz] State, Brazil.

Index entry. This entry combines official IMA/RRUFF species data with published physical-property data — a full written entry hasn’t been published yet. Browse more G minerals or help write this entry.