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Formula: NaAl3(PO4)2(OH)4
Anhydrous phosphate containing hydroxyl
Crystal System: Monoclinic
Specific gravity: 2.98 measured, 2.998 calculated
Hardness: 5½
Streak: White
Colour: Chartreuse yellow, pale yellow, yellow green, colourless; coloured varieties are colourless in transmitted light.
Solubility: Slowly decomposed by HF and by hot sulphuric acid
Environments
Pegmatites
Sedimentary environments
Hydrothermal environments
Most brazilianite occurrences are in granite
pegmatites, where it is found as a relatively late hydrothermal
mineral in cavities. It also occurs in metamorphosed sedimentary deposits and as a sparse component of fracture fillings
in phosphate-rich sedimentary rock.
Associated minerals include montebrasite,
scorzalite, wyllieite,
eosphorite, siderite,
whitlockite, albite,
elbaite, fluorapatite,
muscovite, quartz and
microcline
(R&M 75.40-42, Mindat).
Localities
At the type locality, the Córrego Frio mine, Linópolis, Divino das Laranjeiras, Minas Gerais, Brazil, brazilianite
occurs in cavities in a granite
pegmatite. Associated minerals include
muscovite, albite,
apatite and tourmaline
(HOM).
At Mendes Pimentel, Minas Gerais, Brazil, brazilianite occurs with
muscovite, albite,
apatite and tourmaline
(Dana).
At the Buranga pegmatite, Muhororo, Ngororero District, Western Province, Rwanda, brazilianite occurs with
amblygonite,
lazulite-scorzalite,
augelite, bertossaite and
apatite
(HOM).
The Emmons pegmatite, Greenwood, Oxford county, Maine, USA, is an example of a highly evolved
boron-lithium-cesium-tantalum
enriched pegmatite
(R&M 94.6.505). Brazilianite has been found here associated with
goyazite, montebrasite,
fairfieldite,
eosphorite-childrenite and
kastningite
(R&M 95.2.163-167).
At the Chickering Mine, Walpole, Cheshire county, New Hampshire, USA, brazilianite occurs infrequently as
transparent, colourless crystals to 1.8 mm. The brazilianite occurrence appears to be confined to hydrothermally
altered montebrasite. Other associates include
quartz, albite,
muscovite, and occasionally wardite
(R&M 90.5.414).
At the Palermo No. 1 mine, Groton, Grafton county, New Hampshire, USA, the
pegmatite has three zones:
(1) The outer zone is fine to medium grained and contains quartz,
muscovite, biotite,
albite and schorl.
(2) The intermediate zone is coarse-grained and contains quartz,
muscovite, biotite,
albite,
feldspar variety perthite, beryl,
tourmaline, lazulite, other
phosphates and small amounts of sulphide minerals. The beryl occurs as crystals up
to eight feet long.
(3) The core is of quartz, and contains several other minerals, including single
crystals of triphylite up to fourteen feet long, large feldspar variety
perthite crystals, mica and
beryl.
The brazilianite was found in cavities at the contact of the intermediate zone and the
quartz core.
The pegmatite was traversed by late-stage, relatively low
temperature hydrothermal solutions which attacked the triphylite to form
ludlamite, messelite (?),
siderite, triploidite,
apatite and minor sulphides.
The brazilianite was found in the vicinity of, but not actually in, the altered
triphylite crystals. It occurs as drusy crystals associated with small
quartz crystals, tiny white prisms of
apatite and whitlockite, and in
small cavities in coarsely granular aggregates of feldspar and
quartz. The sequence of formation was
quartz-brazilianite-apatite-whitlockite-quartz
(AM 33.135-141).
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