Thortveitite

 Thortveitite is a mineral consisting of scandium yttrium silicate (Sc,Y)2Si2O7. It is the primary source of scandium. Occurrence is in granitic pegmatites. It was named after Olaus Thortveit, a Norwegian engineer. It is grayish-green, black or gray in color.

Thortveitite
Thortveitite-ea14a.jpg
Thortveitite
General
CategoryMineral
Formula
(repeating unit)
(Sc,Y)2Si2O7
Strunz classification9.BC.05
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H-M symbol)
Space groupC2/m
Identification
Mohs scale hardness5-6
Lustervitreous
Streakgray
Specific gravity3.3-3.8

A transparent gem quality example was found in 2004, and reported in "The Journal of Gemmology", 2008 Volume 31.

The mineral is actually a uniform mixture of oxides of silicon, scandium, and yttrium. It isn't a true compound in itself.

This article uses material from the Wikipedia article
 Metasyntactic variable, which is released under the 
Creative Commons
Attribution-ShareAlike 3.0 Unported License
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