Gagarinite-(Ce)
Appearance
Zajacite or Zajacite-(Ce} is a radioactive mineral: formula Na (REExCa1-x)(REEyCa1-y)F6 where REE means Rare Earth Elements belonging to the Lanthanide series. It has a white vitreous appearance with a conchoidal fracture. Discovered in 1993 at Strange lake, Quebec, it is named after Dr I.S.Zajac who lead the expedition responsible for its discovery.