KOLBECKITE

    Class : Phosphates, arsenates, vanadates
    Subclass : Hydrated phosphates
    Crystal system : Monoclinic
    Chemistry : ScPO4 2H2O
    Rarity : Rare

Kolbeckite is an hydrated scandium phosphate. It is with thortveitite, almost the only two minerals that contain scandium. It is a rare secondary mineral of polymetallic hydrothermal veins and phosphate deposits. It was named in honor of Friedrich Ludwig Wilhelm Kolbeck, geologist at the Mining Academy of Freiberg (Germany). Kolbeckite forms small, short prismatic crystals, sometimes small lamellar individuals united into radiate aggregates. Its color is variable : ordinarily colorless to pale yellow, it becomes bright blue to gray-blue, sometimes apple green when it is impure.

Main photo : Kolbeckite from Magnet Cove, Arkansas, USA © Stephan Wolfsried

Kolbeckite from Bric Colmè, I Cardin, Piedmont, Italy © Giuseppe Finello
Kolbeckite from Bad Gleichenberg, Austria © Stephan Wolfsried
Kolbeckite from Bad Gleichenberg, Austria © Angelo Brambilla
Kolbeckite from Sadisdorf, Saxony, Germany © Stephan Wolfsried

Kolbeckite in the World

The most beautiful crystals, 4 mm individuals, come from Magnet Cove (Arkansas). Kolbeckite is also present in the famous variscite and wardite nodules of the Little Green Monster Mine near Fairfield (Utah), and in a few other American localities. It is also found in the oxidized part of the Horni Slavkov (Czech Republic) and Baia Sprie (Romania) veins, as well as in several localities in India, near Amreli in Gujarat.

Kolbeckite in France

In France, kolbeckite is known from the La Lande quarry (Morbihan).

Twinning

Twins are common on {100}.

Fakes and treatments

No fakes recorded for this mineral species.


Hardness : 3 to 5
Density : 2.36
Fracture : Conchoidal
Streak : White to pale green

TP : Translucent to transparent
RI : 1.572 to 1.601
Birefringence : 0.026
Optical character : Biaxial -
Pleochroism : Strong
Fluorescence : None

Solubility : Acids

Magnetism : NoneRadioactivity : None