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 and/or uranium would make the mineral radioactive. It is black or brown in color. ...
Found on http://en.wikipedia.org/wiki/Zirconolite

zirconolite

(from the article `materials science`) The other candidate is a synthetic rock made of mineral mixtures such as zirconolite and perovskite. These are very insoluble and, in their natural ...
Found on http://www.britannica.com/eb/a-z/z/9
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