GORCEIXITE

    Class : Phosphates, arsenates, vanadates
    Subclass : Hydrated phosphates
    Crystal system : Monoclinic
    Chemistry : BaAl3(PO4)(PO3OH)(OH)6
    Rarity : Quite common

Gorceixite is a barium aluminum phosphate. It is mainly found in granitic pegmatites, lateritic phosphates and many sedimentary rocks. It is also well known in pneumatolytic tin and tungsten deposits, in carbonatites, hydrothermalized dolomites and hydrothermal alteration zones ; it is an accessory component of certain soils, which is also concentrated in alluvium : the "favas" of diamondiferous sands are small gorceixite gravels. It was named in honor of Henrique Gorceix, director of the Ouro Preto School of Mines in Brazil. Gorceixite is a colorless mineral, or often tinged with a more or less deep brown, sometimes pale green or blue. Crystals are rare, and gorceixite generally presents as small 1 cm spheroidal concretions with a fibroradiated texture.

Main photo : Gorceixite from Échassières, Allier, France © Pascal Chollet

Gorceixite from Clara Mine, Germany © Michael Förch
Gorceixite from Clara Mine, Germany © Stephan Wolfsried
Gorceixite from Échassières, Allier, France © Pascal Chollet
Gorceixite from Échassières, Allier, France © Pascal Chollet

Gorceixite in the World

Gorceixite is a mineral common in Minas Gerais (Brazil), in carbonatites (Araxa, where the quantity of gorceixite is estimated at 20 million tons), and especially in "favas" in the gemmiferous alluvium of Rio Abaeto, Bagagem and Douradinho, among others. Gorceixite is also known in many localities, notably in the mineralized veins of Dundas (Tasmania, Australia), and Baia Mare (Romania), in the Ukrainian graphite deposit of Petroskoye, and in the tin and tungsten deposit of Ozark, Missouri.

Gorceixite in France

In France, gorceixite is known in nice samples at Echassières (Allier), at Montebras (Creuse), at Stahlberg (Haut-Rhin) and in certain alluviums in Morbihan.

Twinning

No twin known for this mineral species.

Fakes and treatments

No fakes recorded for this mineral species.


Hardness : 6
Density : 3.03 to 3.18
Fracture : Conchoidal
Streak : White

TP : Translucent to transparent
RI : 1.610 to 1.625
Birefringence : 0.010
Optical character : Uniaxial +
Pleochroism : None
Fluorescence : None

Solubility : -

Magnetism : NoneRadioactivity : None