Anningite-(Ce)

anningite-(Ce)

stetindite-(Ce)

cerianite-(Ce)

cerium

Images

Formula: (Ca_0.5Ce⁴⁺_0.5)(VO₄)
Valence: (Ca_0.5Ce⁴⁺_0.5)(V⁵⁺O₄)
Vanadate, xenotime group, cerium-bearing mineral
Crystal system: Tetragonal
Specific gravity: 3.887 calculated
Hardness: 4 to 5
Streak: White
Colour: Green
Environments

Sedimentary environments

Anningite-(Ce) is a new mineral, approved in 2024 and to date (January 2026) reported only from the type locality.

Localities

At the type locality, the Gara Samani Formation, Timimoun, Timimoun District, Timimoun Province, Algeria, anningite-(Ce) was discovered in cavities within a phosphate-rich coprolite (fossilised faeces). It is very closely related to wakefieldite-(Ce), also of the xenotime group; anningite-(Ce), however, is unusual in that it is one of the few minerals containing essential tetravalent cerium, Ce; other notable examples include stetindite-(Ce) and cerianite-(Ce). Anningite-(Ce) charge balances with a coupled substitution of Ca²⁺ and Ce⁴⁺ for two trivalent cations (AM 111.168-169).
Anningite-(Ce) occurs as small (typically up to 100 μm in length) sheaf-like aggregates composed of crystals 30 to 40 μm in length and about 7 μm across, with a tetragonal columnar habit (Mindat).

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