Yttrialite or Yttrialite-(Y) is a rare yttrium sorosilicate ,Th 7. It forms green to orange yellow masses with conchoidal fracture. It crystallizes in the monoclinic -prismatic crystal system. It has a Mohs hardness 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.