sulfide ores

Sulfide minerals are those in which metallic and non-metallic elements are combined mainly with sulfur (S) and less frequently with selenium (Se), tellurium (Te), arsenic (As), antimony (Sb) and, rarely , bismuth (Bi). In other words, this family of minerals includes the sulfides, tellurides, selenides, arsenides, and antimonides of different transition metals. It also includes sulfosalts in which some metal atoms are replaced by the semimetals arsenic and antimony.

This group is of great economic importance because it includes most of the mineral ores of some of the most important metallic elements in the mining industry. The great variety of coordination polyhedra that sulfur can form means that sulfides can have very varied crystalline structures.

Physical properties of sulfide minerals

Many sulfide minerals are metallic in character, originating from the type of chemical bond between their atoms.

• Most have a metallic appearance and luster.
• They have characteristic colors.
• They give stripes of varied colors. Some stripe white, others black, others dark green, and so on.
• They have a high specific weight that can reach up to 9 g/cm ³ .
• Its hardness is variable. Some are moderately hard, reaching values ​​of 6 on the Mohs hardness scale, while others, particularly sulfosalts, are considerably soft, barely reaching a hardness of 1 or 2.
• Most are opaque.
• Those that are translucent, which are barely 5 or 6, usually have a high refractive index and are only transparent in very thin sections of the mineral, usually near the edges.
• They are generally good conductors of heat and electricity.
• Some sulfide minerals are semiconductors.

Chemical composition

Simple sulfides have an empirical (or molecular, in some cases) formula type M _a X _b . Here, M is a metal (often transition, but it can also be lead or some semimetal) and X, in most cases, is sulfur, although it can also be selenium, tellurium, arsenic or antimony.

Sulfosalts generally consist of oxysalts in which sulfur replaces oxygen. They can also be seen as sulfides in which some metal atoms are replaced by metalloids such as arsenic or antimony and, in some particular cases, bismuth. Regarding the metal, practically all sulfosalts have copper (Cu), silver (Ag) and lead (Pb) as cations.

chemical bond type

Sulfide minerals can present the three main types of chemical bonds. When the cation is a considerably electropositive metal, an ionic bond is formed between sulfide anions (S ^2- ) and the cations of the respective metal.

In some sulfides the bond formed is covalent, especially when it involves elements with similar electronegativities. However, most sulfide minerals are characterized by a metallic bond between their constituent elements. This is precisely what gives them some of their most notable characteristics, such as their metallic luster and their ability to conduct electricity and heat.

Examples of Sulfide Minerals

The family of sulfide minerals and sulfosalts is highly diverse, consisting of hundreds of different minerals. However, only a small number of them are of economic importance as they represent metal ores of industrial interest. Some examples of these minerals are presented in the following table.

References

• EcuRed. (2012, May 9). Sulfides – EcuRed . Retrieved from https://www.ecured.cu/Sulfuros
• Online mining. (2019, May 18). tetrahedrite . Recovered from https://mineriaenlinea.com/rocas_y_minerales/tetraedrita/
• Pascual, CM (nd). Mineralogy – Topic 24: Elements, Sulfides and Sulfosalts . Retrieved from https://es.scribd.com/document/172016308/24
• SGM. (2020, July 21). Classification of minerals . Retrieved from http://www.sgm.gob.mx/Web/MuseoVirtual/Minerales/Clasificacion-de-los-minerales.html
• University of Alicante. (2020, February 7). Sulfides and Sulfosalts . Visu Minerals – UA. Retrieved from https://web.ua.es/es/lpa/minerales-visu/clasificacion-y-caracteristicas/ii-sulfuros-y-sulfosales/sulfuros-y-sulfosales.html#BORNITA