TINSLEYITE

    Class : Phosphates, arsenates, vanadates
    Subclass : Hydrated phosphates
    Crystal system : Monoclinic
    Chemistry : KAl2(PO4)2(OH) 2H2O
    Rarity : Very rare

Tinsleyite is a very rare phosphate of complex granitic pegmatites. It occurs with other secondary phosphates in few pegmatites worldwide. It was named in honor of Frank C. Tinsley for his work in preserving rare minerals found in pegmatites of South Dakota. Tinsleyite forms tabular prismatic crystals intergrown with leucophosphite. It is a brightly colored mineral (magenta to light brownish red or reddish-purple) and frequently zoned, making for attractive compositions with intergrowths of colorless leucophosphite.

Main photo : Tinsleyite from the Tip Top pegmatite, South Dakota, USA © Michael Scott

Tinsleyite in the World

Tinsleyite is known from only a handful of pegmatites in the world, but the most beautiful crystals come from Tip Top (South Dakota) in areas where triphylite has undergone very high oxidation, Sapucaia (Minas Gerais, Brazil) and Bendada (Portugal).

Right photo : Pseudo-octahedral tincalconite from Rio Tinto Borax Mine, California, USA © Rock Currier


Tinsleyite in France

Tinsleyite is not present in the French underground.

Twinning

No twinning known for this mineral species.

Fakes and treatments

No fakes listed for this mineral species.


Hardness : 5
Density : 2.69
Fracture : Irregular
Streak : Pink

TP : Translucent to transparent
RI : 1.591 to 1.604
Birefringence : 0.013
Optical character : Biaxial +
Pleochroism : Strong
Fluorescence : None

Solubility : -

Magnetism : NoneRadioactivity : None