From Wikipedia, the free encyclopedia
Jump to: navigation, search
Category Sorosilicates
(repeating unit)
Strunz classification 9.BC.05
Crystal system Monoclinic
Crystal class Prismatic (2/m)
Color olive-green, brown to black
Crystal symmetry Monoclinic
H-M symbol: (2/m)
Space group: P21/m
References [1][2]

Yttrialite or Yttrialite-(Y) is a rare yttrium thorium sorosilicate mineral with formula: (Y,Th)2Si2O7. It forms green to orange yellow masses with conchoidal fracture. It crystallizes in the monoclinic-prismatic crystal system. It has a Mohs hardness of 5 to 5.5 and a specific gravity of 4.58. It is highly radioactive due to the thorium content.

It is found associated with gadolinite. It was first described in 1889 for an occurrence in the Rode Ranch pegmatite on Baringer Hill, Llano County, Texas. It has also been reported from the Suishouyama pegmatite on Honshū, Japan, and from occurrences in Norway and Sweden.