Zirconolite
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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... Wikipedia
Crystal class: 2M polytype: prismatic (2/m); 3O polytype: dipyramidal (mmm (2/m 2/m 2/m)); 3T polytype: trapezohedral (3 2)
Crystal system: 2M polytype: monoclinic; 3O polytype: orthorhombic; 3T polytype: trigonal