Cadmoindite, formula- (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.
It is an isometric-hexoctahedral mineral containing cadmium, germanium, indium, iron, sulfur, and zinc.
- Category: Sulfide mineral (Thiospinel group)
- Formula: CdIn2S4
- Crystal system: Cubic
- Crystal class: Hexoctahedral (m3m).
- 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
Occurrence: As the bottom layer in fumarolic sublimate crusts.
Association: Pyrite, cadmian wurtzite, rhenium disulfide, greenockite, lead-bismuth sulfide.
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.