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Category Oxide mineral
(repeating unit)
Strunz classification 4.DL.05
Crystal system Isometric
Crystal class Hexoctahedral (m3m)
H-M symbol: (4/m 3 2/m)
Unit cell a = 5.02 Å, Z = 4
Color black, reddish brown
Crystal habit Crystalline, metamict, pseudocubic
Cleavage none
Fracture brittle
Luster Resinous
Streak brownish grey
Diaphaneity Subtranslucent to opaque[1]
Density 4.7

Zirkelite is an oxide mineral with formula: (Ca,Th,Ce)Zr(Ti,Nb)2O7. It occurs as well-formed fine sized isometric crystals. It is a black, brown or yellow mineral with a hardness of 5.5 and a specific gravity of 4.7.

Name and discovery[edit]

Zirkelite was first discovered in Brazil in 1895. It was named for German petrographer Ferdinand Zirkel (1838–1912).


Initial discovery was from the Jacupiranga carbonatite, Sao Paulo, Brazil. It is also found in Canada, Kazakhstan, Norway, Russia, South Africa, the United Kingdom, and the United States.