Tyrrellite, Cu(Co_0.68Ni_0.32)₂Se₄, isostructural with spinel

Tyrrellite, Cu(Co,Ni)₂Se₄, is a normal spinel containing Cu in a tetra­hedral coordination.

Isokite, CaMg(PO₄)F_0.8(OH)_0.2, isomorphous with titanite

Isokite, ideally CaMg(PO₄)F, is isomorphous with C2/c titanite and consists of PO₄, MgO₄F₂, and CaO₆F polyhedra.

Kolbeckite, ScPO₄·2H₂O, isomorphous with metavariscite

This study presents the first structural report of kolbeckite, with the ideal formula ScPO₄·2H₂O (scandium phosphate dihydrate), based on single-crystal X-ray diffraction data. Kolbeckite belongs to the metavariscite mineral group, in which each PO₄ tetra­hedron shares four vertices with four ScO₄(H₂O)₂ octa­hedra and vice versa, forming a three-dimensional network of polyhedra.

Iranite, CuPb₁₀(CrO₄)₆(SiO₄)₂(OH)₂, isomorphous with hemihedrite

Iranite is isomorphous with hemihedrite, ZnPb₁₀(CrO₄)₆(SiO₄)₂F₂. The SiO₄ and CrO₄ tetra­hedra and CuO₄(OH)₂ octa­hedra form layers parallel to (120) that are held together by Pb²⁺ cations.