Formula: SrAl3(PO4)(PO3OH)(OH)6
Phosphate containing hydroxyl, crandallite group, forms series with
crandallite and with gorceixite
Specific gravity: 3.26
Hardness: 4½ to 5
Streak: White
Colour: White, yellow, honey-yellow, pink, lilac, orange or colourless; colourless in transmitted light
Solubility: Slowly soluble in acids
Environments
Pegmatites
Carbonatites
Sedimentary environments
Hydrothermal environments
Goyazite occurs in granitic pegmatites, in hydrothermal argillic alteration zones,
in kaolinitic claystones derived from air-fall
volcanic tuff, in sedimentary phosphate deposits, in carbonatites and in detrital deposits,
including diamantiferous sands (Mindat, HOM).
Associated minerals include apatite, baryte,
diamond, herderite,
kaolinite, monazite,
pyrite and quartz
(Mindat).
Localities
The type locality is Diamantina, Minas Gerais, Brazil, as placer nodules
(Mindat).
At the Alto Benedito pegmatite, Frei Martinho, Borborema mineral province, Paraíba, Brazil, goyazite is associated with
herderite, apatite and
quartz
(HOM).
In the Simplon tunnel, Switzerland, goyazite occurs on anhydrite
(Dana).
At the Wigu carbonatite, Tanzania, goyazite is associated with monazite,
sphalerite, pyrite,
baryte and quartz
(HOM).
At the Belaya Kalitva region, Donetz basin, Ukraine, goyazite occurs in limestone
with baryte, pyrite and
quartz
(Dana).
At the Emmons pegmatite, Greenwood, Oxford county, Maine, USA, goyazite has been found as crystals to several mm, also
schorl replaced by muscovite has been found with
an overgrowth of goyazite and hydroxylherderite. A granular mixture of
montebrasite and goyazite has been found. The Emmons pegmatite is an example of
a highly evolved boron-lithium-cesium-tantalum enriched pegmatite
(R&M 94.6.508).
At the Chickering mine, Cheshire county, New Hampshire, USA, goyazite has been found in cavities adjacent to
altered montebrasite, associated with quartz,
albite and fluorapatite
(R&M 90.5.417).
Common impurities: Ba,F
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