Sulphides refers to a mineral group where sulphur is combined with one or more metals. The sulphides form an important class of minerals that includes the majority of the ore minerals. With them are classed the similar but rarer sulpharsenides, arsenides, and tellurides. Most of the sulphide minerals are opaque with distinctive colours and characteristically coloured streaks. Those that are non-opaque, such as cinnabar, realgar, and orpiment, have high refractive indices and transmit light only on thin edges.
The general formula for the sulphides is given as XmZn, in which X represents the metallic elements and Z the non-metallic element. The general order of listing of the various minerals is in a decreasing ratio of X:Z. The sulphides can be divided into small groups of similar structures but it is difficult to make broad generalizations about their structure. Regular octahedral or tetrahedral coordination about sulphur is found in many simple sulphides such as in galena, PbS, (with an NaCI type structure), and in sphalerite, Zns. In more complex sulphides, as well as sulphosalts, distorted coordination polyhedra may be found. Many of the sulphides have ionic and covalent bonding, whereas others, displaying most of the properties of metals, have metallic bonding characteristics. Research Sulphides
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Rocks & Minerals
Research Sulphides
