allaniteY

AllaniteY is a mineral species belonging to the allanite group, which are sorosilicate minerals within the epidote supergroup. It is characterized by the presence of yttrium as a significant substituting element. AllaniteY is an opaque to translucent mineral, typically black, brownish-black, or dark brown in color. It often exhibits a vitreous to greasy luster.

The chemical formula for allaniteY is (Ca,REE,Y)2(Al,Fe)3(SiO4)(SiO3O)(OH), where REE represents rare earth elements and Y denotes yttrium. The 'Y' in its designation specifically indicates that yttrium plays a prominent role in its crystal structure, distinguishing it from other members of the allanite series where other rare earth elements might be dominant. AllaniteY crystallizes in the monoclinic crystal system, forming prismatic or granular aggregates.

It is found in a variety of igneous and metamorphic rocks, including granites, diorites, gabbros, gneisses, and schists. AllaniteY typically forms as a minor accessory mineral. Its presence can be indicative of specific geological conditions and the overall rare earth element and yttrium content of the host rock. While not a primary ore mineral, it can be a source of rare earth elements and yttrium during geological weathering and in certain placer deposits.