Anningite-(Ce) ideally (Ca0.5Ce4+0.5)(VO4), was found within a phosphate coprolite from the sand-dominated sediments of the Gara Samani Formation, Algeria. As a tetragonal anhydrous vanadate, this mineral is classified in the xenotime group. It occurs in rock cavities and forms small (typically up to 100 μm in length) sheaf-like aggregates composed of crystals 30–40 μm in length and ∼7 μm in diameter. Anningite-(Ce) crystals are green with a vitreous lustre. No cleavage is observed and the fracture is uneven or conchoidal. Its empirical formula, calculated on the basis of 4 oxygen atoms, can be written as (Ca0.52Ce4+0.47Y3+0.01)Σ1.00[(VO4)0.88(PO4)0.05(SO4)0.06(SiO4)0.01]Σ1.00. The calculated density is 3.887 g/cm3. Anningite-(Ce) is tetragonal with space group I41/amd and unit-cell parameters a = 7.1500(4) Å, c = 6.3343(7) Å, and V = 323.82(5) Å3. Anningite-(Ce) is isostructural with wakefieldite-(Ce).
