Zirconolite

Zirconolite is a mineral, calcium zirconium titanate; formula CaZrTi₂O₇. Some examples of the mineral may also contain thorium, uranium, cerium, niobium and iron; the presence of thorium or uranium would make the mineral radioactive. It is black or brown in color.^[3]

Zirconolite
Black crystal aggregates of the rare zirconium mineral zirconolite.
General
Category	Oxide minerals
Formula	CaZrTi2O7
IMA symbol	Zrc[1]
Strunz classification	4.DH.30
Crystal system	2M polytype: monoclinic 3O polytype: orthorhombic 3T polytype: trigonal
Crystal class	2M polytype: prismatic (2/m) 3O polytype: dipyramidal (mmm (2/m 2/m 2/m)) 3T polytype: trapezohedral (3 2)
Identification
Color	Black to brown, red
Luster	Resinous, sub-Metallic
Streak	Dark brown, brownish yellow
Diaphaneity	Translucent, opaque
References	[2]