Mineral description : Knopite

Possible knopite crystals from Alnö. As black cubes to the lower right.

Mineral class	Oxides : Perovskit - Pyrochlor - Columbite group
Chemical formula	(Ca,Ce)TiO2
Crystal system	Orthorombic.
Habitus	As small cubic crystals or in massive form.
Cleavage	Imperfect in one direction.
Hardness	5.5
Density	4.2
Color	Black, opaque.
Streak	(this one, brownish black)
Luster	Metallic.
Description
Occurance
Associates
Notes	Not approved as a separate mineral by IMA. It is regarded as a cerium enriched perovskite or a mixture of perovskite / ilmenite / anatas / rutil / titanite and Nb enriched aeschynite-(Ce). Knopite from Alnö contains about 4-5% ceriun oxide. Litterature references : GFF 16 (pg 73), GFF 17 (pg 155), SGU Ca36 (pg 69)
Locations	A rare mineral Alnö area, Medelpad. As small black cubes in sövite together with perowskite. Localities outside scandinavia Vetralla, Italy. In volcanic trachite bombs. As cubic crystals up to 1 mm in size together with flogopite, titanite and apatite.

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