MORAESITE

    Class : Phosphates, arsenates, vanadates
    Subclass : Hydrated phosphates
    Crystal system : Monoclinic
    Chemistry : Be2(PO4)(OH) 4H2O
    Rarity : Very rare

An extremely rare beryllium mineral, moraesite is a secondary hydrated phosphate which forms in the final stages of crystallization of granitic pegmatites, where it very often coexists with beryl, frondelite and triphyllite. It was named in honor of Luciano Jaques Moraes, Brazilian mineralogist and geologist. Moraesite is a white mineral which usually forms acicular or fibrous crystals, exceptionally measuring 5 mm, often united in spherolitic aggregates reminiscent of okenite; it can also form geodic or felt encrustations.

Main photo : Moraesite de Pomarolli farm, Linópolis, Minas Gerais, Brazil © Gianfranco Ciccolini

Moraesite in the World

Moraesite is found mainly in the pegmatites of the American East and Brazilian Minas Gerais. In the United States, the famous pegmatites of Maine (Greenwood, Mount Mica and Newry) and New Hampshire (Palermo) provided the best samples. In Brazil, we note in particular Sapucaia, the discovery deposit, where moraesite crystallizes in geodes adjacent or internal to beryl crystals.

Moraesite in France

In France, moraesite is present in the pegmatite of Arnac-la-Poste (Haute-Vienne) as well as in the Puech de Leguo quarry (Aveyron).

Twinning

No twin known for this mineral species.

Fakes and treatments

No fakes recorded for this mineral species.


Hardness : Undetermined
Density : 1.81
Fracture : Undetermined
Streak : White

TP : Translucent
RI : 1.462 to 1.490
Birefringence : 0.028
Optical character : Biaxial -
Pleochroism : None
Fluorescence : None

Solubility : Acids

Magnetism : NoneRadioactivity : None