Zirkelite

Zirkelite
General
Category	Oxide mineral
Formula (repeating unit)	(Ti,Ca,Zr)O(2-x)
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
Identification
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
Other characteristics	Radioactive

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

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

Occurrence

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.

References

• Webmineral data
• Mindat localities
• Mineral Data Publishing