Brazilianite

Brazilianite is a rarely occurring mineral from the mineral class of " phosphates, arsenates and vanadates ." It crystallizes in the monoclinic crystal system with the chemical composition NaAl3 [( OH) 2 | PO4 ] 2, and usually develops transparent to translucent, short prismatic or isometric crystals, but also radial-, granular or massive aggregates.

Special Features

Reiner brazilianite is colorless or white. However, it may be by Fremdbemengungen yellowish to greenish yellow color.

Boric acid and borax to etch the mineral hydrofluoric acid destroys it.

Etymology and history

First described scientifically and is recognized as a separate mineral was the brazilianite 1945 Poughkeepsie and Henderson. As a type locality applies Conselheiro Pena in Minas Gerais in Brazil and after this locality (Brazil ), the mineral was named. The brazilianite was known however, had already, but was mistaken for chrysoberyl.

Classification

In the old ( 8th edition ) and new classification of minerals according to Strunz ( 9th edition ) of the brazilianite belongs to the department of " water clear phosphates with foreign anions ." The new Strunz'sche Mineral classification divided here but precisely according to the size of the involved cations and the molar ratio between foreign anions and phosphate complex. The mineral is now in accordance with the subdivision "With medium -sized and large cations, and the molar ratio (OH, etc.): RO 4 = 2: 1 or 2.5: 1"

Education and Locations

Brazilianite formed from hydrothermal solutions in phosphate -rich zones of granite pegmatites, but can also occur in metamorphosed sedimentary rocks. It occurs in this case in paragenesis with different minerals, so among other things, with albite, Amblygonite, apatites, Augelith, Bertossait, muscovite, quartz, minerals of the tourmaline and whitlockite.

So far brazilianite could be detected at 45 localities (as of 2009): Salta, Argentina; East Gippsland Shire in Australia; Paraíba and Rio Grande do Norte in the Northeast region, Espírito Santo and Minas Gerais in the southeastern region of Brazil; Waidhaus in Germany; Ébreuil in France; at Dawson in Canada; Karibib in Namibia; Spittal an der Drau in Austria; Gatumba in Rwanda; Zamora in Spain; Richtersveld in South Africa; Moravia in the Czech Republic; as well as in the U.S. State Arizona, Connecticut, Maine, New Hampshire and South Dakota.

Crystal structure

Brazilianite crystallizes in the monoclinic space group P21 / n with lattice parameters a = 11.233 Å; b = 10.142 Å; c = 7.097 Å and β = 97.37 ° and four formula units per unit cell.

Use as a gemstone

Brazilianite is processed exclusively for gems, however, is not yet widely used as a relatively new gem mineral. Since the stone only has about the hardness of glass, it is against stress sensitive in jewelry making and while wearing and can easily be damaged as an arm or finger jewelry for everyday use. Confusion due to its color consists among other things, Amblygonite, apatite, chrysoberyl, beryl and topaz.