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Brazilianite facts for kids

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Brazilianite-4jg60a
Brasilianite from the municipality of Conselheiro Pena (MG)

Brazilianite is a typically yellow-green phosphate mineral, most commonly found in phosphate-rich pegmatites. It was originally found in Brazil, and was named after the country in which it was first found.

Brazilianite
Brazilianite from type locality, Conselheiro Pena, Minas Gerais, Brazil
General
Category Phosphate minerals
Formula

(repeating unit)

NaAl3(PO4)2(OH)4

sodium aluminium phosphate hydroxide

Strunz classification 8.BK.05
Crystal system Monoclinic
Crystal class Prismatic (2/m)

(same H-M symbol)

Space group P21/n
Unit cell a = 11.229 Å,

b = 10.142 Å, c = 7.098 Å; β = 97.4°; Z = 4

Identification
Color Yellow, green, colorless
Crystal habit Prismatic crystals, may be radially-fibrous or globular druses
Cleavage (010) Distinct to good
Fracture Conchoidal
Mohs scale hardness 5.5
Luster Vitreous
Streak White
Diaphaneity Transparent to translucent
Specific gravity 2.98
Optical properties Biaxial (+)
Refractive index nα = 1.602 nβ = 1.609 nγ = 1.621 - 1.623
Birefringence δ = 0.019 - 0.021
References

It occurs in the form of perfect crystals grouped in druses, in pegmatites, and is often of precious-stone quality. One noted deposit of brazilianite is in the surroundings of Conselheiro Pena, in Minas Gerais, Brazil.

Some of these are found on leaves of muscovite with their strong silvery glitter, ingrown in their parent rock. The crystals, dark greenish-yellow to olive-green, sometimes measure up to 12 cm (4.7 in) in length and 8 cm (3.1 in) in width. Crystals of similar shape and dimensions have been discovered in another deposit in Minas Gerais, near Mantena, but they lack the perfection of the crystal form. Many brazilianites found in mineral collections originated from the Palermo and the Charles Davis mines in Grafton County, New Hampshire.

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