Allanite - Wikipedia
Allanite (also called orthite) is a sorosilicate group of minerals within the broader epidote group that contain a significant amount of rare-earth elements.The mineral occurs mainly in metamorphosed clay-rich sediments and felsic igneous rocks. It has the general formula A 2 M 3 Si 3 O 12 [OH], where the A sites can contain large cations such as Ca 2+, Sr 2+, and rare-earth elements, and the ...