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Formula: SrAl3(PO4)(PO3OH)(OH)6
Phosphate containing hydroxyl, plumbogummite group,
alunite supergroup, forms series with
crandallite and with
gorceixite, strontium-bearing
mineral
Crystal System: Trigonal
Specific gravity: 3.26 measured, 3.29 calculated
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
Common impurities: Ba,F
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).
At the Keyes Mica Quarries, Orange, Grafton County, New Hampshire, USA, the
pegmatites are beryl-type
rare-element (RE) pegmatites.
The Number 1 mine exposed a pegmatite that shows the most
complex zonation and diverse mineralogy of any of the Keyes
pegmatites. Six zones are distinguished, as follows, proceeding
inward from the margins of the pegmatite:
(1) quartz-muscovite-plagioclase
border zone, 2.5 to 30.5 cm thick
(2) plagioclase-quartz-muscovite
wall zone, 0.3 to 2.4 metres thick
(3) plagioclase-quartz-perthite-biotite
outer intermediate zone, 0.3 to 5.2 metres thick, with lesser muscovite
(4) quartz-plagioclase-muscovite
middle intermediate zone, 15.2 to 61.0 cm thick
(5) perthite-quartz inner intermediate zone, 0.9 to 4.6 meters thick
(6) quartz core, 1.5 to 3.0 metres across
The inner and outer intermediate zones contained perthite crystals up to
1.2 meters in size that were altered to vuggy
albite-muscovite with
fluorapatite crystals. This unit presumably was the source of the
albite, muscovite,
fluorapatite, quartz and other
crystallised minerals found in pieces of vuggy albite
rock on the dumps next to the mine.
The middle intermediate zone produced sheet mica with accessory minerals including
tourmaline, graftonite,
triphylite, vivianite,
pyrite, pyrrhotite, and
beryl crystals to 30.5 cm long and 12.7 cm across.
Goyazite occurs as white pseudocubic crystals to about 1 mm. One specimen is a cabinet sized specimen with a
6 cm cavity richly lined with microsized goyazite as well as siderite
and quartz crystals to several millimeters
(R&M 97.4.318).
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