Gemmology
English | Български
Where am I? > Home > Classification > Brazilianite


Quick navigation selector

Brazilianite

Class: Phosphates, arsenates, vanadates

A hydrothermal mineral in phosphate-rich zones of granite pegmatites; also in metamorphosed sedimentary deposits (Anthony et al., 2001—2005). Faceted specimens are rare.

Original description: Pough, F. H., Henderson, E. P., 1945. Brazilianite, a new phosphate mineral — American Mineralogist 30: 572—582 [view in ‘Library’].

Type locality: Córrego Frio mine, Linópolis, Minas Gerais, Brazil.

Type material: National Museum of Natural History, Smithsonian Institution, Washington, DC, USA, 105048 (Anthony et al., 2001—2005).

Etymology: for the type locality country, Brazil.

Distribution: Brazil: Minas Gerais, Linópolis, from the Córrego Frio and other nearby pegmatite mines; Canada: Yukon Territory, in the Big Fish River — Rapid Creek area; Germany: Bavaria, Hagendorf; Rwanda: from the Buranga pegmatite, near Gatumba; USA: Maine, Oxford Co., at the Bell Pit; New Hampshire, Grafton Co. and Sullivan Co. (Anthony et al., 2001—2005).

Chemistry

NaAl3(PO4)2(OH)4

Essential elements: hydrogen (H), oxygen (O), sodium (Na), aluminium (Al), phosphorus (P).

Crystal data

Crystallography: monoclinic — prismatic. Crystal habit: crystals typically equant, elongated along [100], to 20 cm; may be radial fibrous, globular (Anthony et al., 2001—2005).

Physical properties

Cleavage: on {010}, good (Anthony et al., 2001—2005). Fracture: conchoidal (Arem, 1987: 57). Tenacity: brittle (Arem, 1987: 57). Hardness: 5.5 (Arem, 1987: 57). Density: 2.98—2.99 g/cm3 (Lazzarelli, 2012). Luminescence: none (Arem, 1987: 57). Other: slowly decomposed by hydrogen fluoride and by hot sulfuric acid.

Optical properties

Colour: chartreuse-yellow, pale yellow, yellow-green; colourless in transmitted light (Anthony et al., 2001—2005). Diaphaneity: transparent (Anthony et al., 2001—2005). Lustre: vitreous (Arem, 1987: 57). Refractive index: 1.602—1.625 — anisotropic [biaxial (+)] (Lazzarelli, 2012). Birefringence: 0.018—0.021. Dispersion: 0.014 (Arem, 1987: 57). Pleochroism: weak (Arem, 1987: 57).

Material from ‘Repository’

2 specimens: 0002 — 0.53 ct, Brazil, Minas Gerais, Rio Doce, Divino das Laranjeiras, Linópolis; 0127 — 0.81 ct, Brazil, Minas Gerais, Rio Doce, Divino das Laranjeiras, Linópolis.


Gallery view