WHITLOCKITE

    Class : Phosphates, arsenates, vanadates
    Subclass : Anhydrous phosphates
    Crystal system : Trigonal
    Chemistry : Ca9(Mg,Fe)(PO4)6(PO3OH)
    Rarity : Uncommon

Whitlockite is a secondary calcium phosphate of complex granitic pegmatites that is sometimes also found in phosphate deposits or in caves, crystallizing at the expense of guano. It is also the constituent of dental plaque. It was named in honor of Herbert Percy Whitlock, Curator of the Department of Mineralogy at the American Museum of Natural History in New York. Whitlockite forms rhombohedral or tabular crystals of up to 2 cm, colorless to white, yellowish-gray to pale yellow, sometimes pinkish ; it is also known in granular to earthy masses.

Main photo : Whitlockite from Big Fish River, Yukon, Canada © Rob Lavinsky

Whitlockite from Big Fish River, Yukon, Canada © Rob Lavinsky
Whitlockite from Tip Top Mine, South Dakota, USA © Gianfranco Ciccolini
Whitlockite on jahnsite from Tip Top Mine, South Dakota, USA © Stephan Wolfsried
Whitlockite from Tip Top Mine, South Dakota, USA © Stephan Wolfsried

Whitlockite in the World

Whitlockite is relatively common in pegmatites in South Dakota, Maine, and New Hampshire, and in other pegmatites around the world (Namibia, Canada, etc...). It is also known in phosphate deposits in the Antilles (Curaçao) as well as in caves in Algeria, Malaysia and Puerto Rico where it crystallizes on guano. It has also been identified in lunar rocks.

Withlockite in France

In France, whitlockite is known in the Guano cave (Alpes-Maritimes).

Twinning

No twinning known for this mineral species.

Fakes and treatments

No fakes listed for this mineral species.


Hardness : 5
Density : 3.12
Fracture : Irregular to sub-conchoidal
Streak : White

TP : Translucent to transparent
RI : 1.626 to 1.629
Birefringence : 0.003
Optical character : Uniaxial -
Pleochroism : None
Fluorescence : None

Solubility : Nitric acid, hydrochloric acid

Magnetism : NoneRadioactivity : None

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