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. The yellow, yellow-brown, pink-red or purple eudialyte has a glass luster, a white stripe color and an imperfect cleavage along the crystal plane [0001]. The average density is 2.9 and the hardness is 5 to 5.5. The crystal system is trigonal and the mineral is mildly radioactive. The 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, composed of the words εὖ eu, good. and διάλυτος diálutos, fissile. The mineral eudialyte is mainly found in nepheline syenites. The type location is the Julianehåb district in Greenland. The mineral is also found in Quebec, Canada.