Britholite-(Ce) Locality: Tuperssuatsiat Bay, Tunugdliarfik Firth (Eriksfjord), Ilimaussaq complex , Narsaq , Kitaa (West Greenland) Province, Greenland ( Locality at mindat.org ) Size: 3.9 x 2.9 x 1.0 cm. A very lustrous, compound crystal of this very rare mineral from the Greenland suite. I am told that it is uncommon in such size and richness. The faces on the left and top are probably natural, with the lower-right faces being cleavage planes. This specimen was exchanged to Harvard University from the University of Copenhagen Museum collection, before being traded out to Lawrence Conklin. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Britholite-(Ce)
Britholite-(Ce) is a rare radioactive mineral with the chemical formula (Ce,Ca)5(SiO4)3OH. It comes in a variety of different colors. Its type locality is Naujakasik (Naajakasik), Tunulliarfik Fjord, Ilímaussaq complex, Narsaq, Kujalleq, Greenland.
Intro adapted from Wikipedia (CC BY-SA).
Britholite-(Ce) is an IMA-recognized mineral species in the silicate class, with the chemical formula (Ce,Ca)₅(SiO₄)₃(OH).
It crystallizes in the monoclinic crystal system (space group P6_3). It is a member of the Apatite structural group.
Key properties: Mohs hardness 5; specific gravity 4.2–4.69; Adamantine luster; optically uniaxial.
IMA symbol Bri-Ce, IMA status: approved, named in 1901.
Found in nepheline syenites, pegmatites, and contact deposits related to them.
It is found associated with Zircon, pyrochlore, titanite, fluorite, diopside, andradite, allanite, vesuvianite.
Its name comes from the Greek for weight, in allusion to its density, and its content of cerium.