My account : Sign in

My orders

Your cart is empty.


>> Group(s) : silicates
See the pictures :

Discovered in 1865 its name comes from Greek showing that its chemical formula was a real "mystery" to solve.

Exploited sites

It is found in Russia's Kola Peninsula, Scotland, Greenland, Canada, United States, Tasmania, Australia, China ...

See pictures of the mines / other pictures

Use in jewelry

only a collection stone, rarely cut

Looking alike stones

pyrolusite , tourmaline , wolframite , ilvaite

Chemical characteristics

complex silicate

Physical characteristics

Main color : black

Other colors : brown, grey

velvety black

Color of streak : brown, red

Luster : adamantine, greasy

Hardness : 5.5 to 6.0

Density : 3.70 to 3.90

Cleavage : good

Fracture : uneven

Optical properties

Transparency : translucent, opaque

Refractive Index : 1.780 - 1.900

Double refraction : 0.090

Strong biaxial (+)

visible double refraction : no

Pleochroism : definite

Number of colors : 3

Different shades of brown to black, but difficult to observe

Fluorescence : none


Lamellaror prismatic


Crystal system : triclinic

Other informations
For sale in our boutiques
See all offers