Description
The mineral eudialyte (Eudialite) is a chlorine-containing sodium-calcium-cerium-iron-manganese-yttrium-zirconium silicate with the chemical formula Na4(Ca,Ce)2(Fe2+,Mn,Y)ZrSi8O22(OH,Cl)2. The mineral belongs to the cyclosilicates. Yellow, yellow-brown, pinkish-red, or purple eudialyte has a vitreous luster, a white streak color, and imperfect cleavage along the [0001] crystal plane. Its average density is 2.9 and its hardness is 5 to 5.5. The crystal system is trigonal, and the mineral is mildly radioactive. Its gamma ray value, according to the American Petroleum Institute, is 7287.91. The name of the mineral eudialyte is derived from the Greek εὐδιάλυτος eudiálutos, easily fissile[1], composed of the words εὖ eu, good. and διάλυτος diálutos, fissile. The mineral eudialyte occurs mainly in nepheline syenites. The type locality is the Julianehåb district in Greenland. The mineral is also found in Quebec, Canada.
