Arrojadite - Encyclopedia

    Class : Phosphates, arsenates, vanadates
    Subclass : Anhydrous phosphates
    Crystal System : Monoclinic
    Chemistry : KNa4CaFe10Mn4Al(PO4)12(OH)2
    Rarity : Uncommon to rare

Arrojadite is a complex primary phosphate of granitic pegmatites. Its name was given to it in honor of the Brazilian geologist Miguel Arrojada Ribiero. It is almost unknown in automorphic crystals but mostly forms cleavable masses of dark to very dark green.

Photos : Arrojadite of Rapid Creek, Yukon, Canada © Gianfranco Ciccolini

Arrojadite in the World

It is a usual mineral of the American pegmatites of New Hampshire (Palermo 1 and 2 mines of North Groton, Newport...) and of South Dakota, in particular of the Nickel Plate and White Cap mines, near Keystone, which provided substantial masses. Arrojadite is also known, among other localities, in the pegmatites of Zimbabwe (district of Miami), Galileia (Minas Gerais, Brazil) and Mangualde (Portugal).

Arrojadite in France

This mineral is not known in the French underground.

Twinning and special crystallizations

No known twin for this mineral species

Fakes and treatments

No fake or treatments identified for this mineral species.

Hardness : 5
Density : 3,52
Fracture : Irregular
Trace : White

TP : Translucent to transparent
RI : 1.664 to 1.675
Birefringence : 0.011
Optical character : Biaxial +
Pleochroism : Visible
Fluorescence : None

Solubility : Nitric acid, hydrochloric acid

Magnetism : None
Radioactivity : None


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