The thiospinel group is a group of
sulfide minerals
The sulfide minerals are a class of minerals containing sulfide (S2−) or disulfide () as the major anion. Some sulfide minerals are economically important as metal ores. The sulfide class also includes the selenides, the tellurides, the ar ...
with a general formula where A is nominally a +2 metal, B is a +3 metal and X is -2 sulfide or similar anion (selenide or telluride). ''Thio'' refers to sulfur and ''spinel'' indicates their
isometric spinel
Spinel () is the magnesium/aluminium member of the larger spinel group of minerals. It has the formula in the cubic crystal system. Its name comes from the Latin word , a diminutive form of ''spine,'' in reference to its pointed crystals.
Prop ...
-like structure.
[Thiospinel group on Mindat]
/ref>
As the chalcogen
The chalcogens (ore forming) ( ) are the chemical elements in group 16 of the periodic table. This group is also known as the oxygen family. Group 16 consists of the elements oxygen (O), sulfur (S), selenium (Se), tellurium (Te), and the rad ...
s S, Se and Te are less electronegative
Electronegativity, symbolized as , is the tendency for an atom of a given chemical element to attract shared electrons (or electron density) when forming a chemical bond. An atom's electronegativity is affected by both its atomic number and the d ...
than oxygen, the bonding in these materials is generally more covalent
A covalent bond is a chemical bond that involves the sharing of electrons to form electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs. The stable balance of attractive and repulsive forces between atom ...
than in the oxospinels. Some are (magnetic
Magnetism is the class of physical attributes that occur through a magnetic field, which allows objects to attract or repel each other. Because both electric currents and magnetic moments of elementary particles give rise to a magnetic field, m ...
) semiconductor
A semiconductor is a material with electrical conductivity between that of a conductor and an insulator. Its conductivity can be modified by adding impurities (" doping") to its crystal structure. When two regions with different doping level ...
s but others display, at times complicated, metallic behavior, often coupled with equally complicated magnetic properties. The assignment of oxidation state
In chemistry, the oxidation state, or oxidation number, is the hypothetical Electrical charge, charge of an atom if all of its Chemical bond, bonds to other atoms are fully Ionic bond, ionic. It describes the degree of oxidation (loss of electrons ...
s is also not always as straightforward as in the more ionic oxocompounds, as is shown in the case of carrollite.
Group members include:
* Cadmoindite –
* Carrollite –
* Fletcherite –
* Greigite –
* Indite –
* Kalininite –
* Linnaeite –
* Polydymite -
* Siegenite –
* Tyrrellite
Tyrrellite is a selenide mineral that has a chemical formula of . It has been found in the Goldfields District in northern Saskatchewan, as well as in the Petrovice deposit, Czech Republic. It is named after the Canadian geologist Joseph Burr Ty ...
–
* Violarite
Violarite ( Fe2+ Ni23+ S4) is a supergene sulfide mineral associated with the weathering and oxidation of primary pentlandite nickel sulfide ore minerals.
Violarite crystallises in the isometric system, with a hardness of 4.5 to 5.5 and a speci ...
–
References
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