Eudialyte

Eudialyte is a member of the trigonal cyclosilicates which there are many members but eudialyte is the only member used as a gemstone. It is a micro ore of zirconium.

Eudialyte is mildly radioactive and in small amounts is not dangerous however long term handling of a quantity may yield dangers. 

Eudialite is usually found in small crystals and cut into gemstones or spheres in its matrix. It is an acid sensitive small crystal with a hardness of about 5 on the mohs scale.