Anhydrous phosphate containing hydroxyl
Specific gravity: 2.98
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
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).
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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