Caldasite

Caldasite (Portuguese:Caldasito, German:Zirkonglaskopf, Spanish:Caldasita) is a rare uraniferous ore of zirconium found in the Poços de Caldas massif, located in the states of Minas Gerais and São Paulo, Brazil.

It is most often found as a dark gray, very dense, hard rock. It also appears as a friable brown substance.