| Cadmoindite | |
|---|---|
Cadmoindite, from Kudriavy Volcano, Far Eastern Region, Russian Federation | |
| General | |
| Category | Sulfide mineral Thiospinel group Spinel structural group |
| Formula | CdIn2S4 |
| IMA symbol | Cad |
| Strunz classification | 2.DA.05 |
| Crystal system | Cubic |
| Crystal class | Hexoctahedral (m3m) H-M symbol (4/m 3 2/m) |
| Space group | Fd3m |
| Unit cell | a = 10.81 Å; Z = 8 |
| Identification | |
| Formula mass | 470.32 g/mol |
| Color | Black to dark brown |
| Crystal habit | Microscopic octahedral crystals |
| Fracture | Conchoidal |
| Luster | Adamantine |
| Diaphaneity | translucent |
| Optical properties | Isotropic |
| References | |
Cadmoindite (CdIn2S4) is a rare cadmium indium sulfide mineral discovered in Siberia around the vent of a high-temperature (450–600 °C) fumarole at the Kudriavy volcano, Iturup Island in the Kuril Islands. It has also been reported from the Kateřina Coal Mine in Bohemia, Czech Republic.
CdIn2S4 exhibits the spinel structure, which can be described by a cubic unit cell with 8 tetrahedrally coordinated and 16 tetrahedrally coordinated cation sites. The distribution of Cd(II) and In(III) over the cation sites is difficult to elucidate from standard X-ray diffraction techniques because the two species are isoelectronic, but both Raman spectroscopy measurements on synthetic samples and density functional theory simulations indicate that about 20% of the tetrahedral sites are occupied by In(III) cations.