The importance of the sulphide and related minerals as ores need not be emphasized as it has been a known fact since ancient times. Nowadays many of them have wide additional use as diamagnetic, paramagnetic and antiferromagnetic semiconductors, as optically active crystals, etc. This explains the extensive studies carried out during the last few decades, both on naturally occurring sulphides sensu lato, and on artificially obtained analogous phases. The literature dealing with these compounds is enormous and almost impossible to grasp, being dispersed in the field of mineralogy, petrology, economic mineral deposits, chemistry, physical chemistry, solid state physics, metallurgy, etc. Perhaps that is the reason why there are limited publications generalizing one or another aspect of them only.

The present monograph is an attempt to bring together data on crystal chemistry and paragenetic trends of sulphide and related minerals, and to evolve a more near-nature systematics for them. For this purpose an original comparative study of the structures of these minerals is presented and pertinent data and diagrams on natural phase relationships, deduced from their assemblages in nature and from artificial systems are used. Apart from certain original ideas put forward by the authors in the text, entirely new in the monograph is the systematics of all so far known and named sulphide and related minerals, presented with pertinent crystal chemical data (space groups, unit cell dimensions) and indicative X-ray spacings. The monograph is intended primarily for mineralogists, geochemists, petrologists, ore deposits specialists, and for scientists of related branches of knowledge, as well as for students of such trends.

Ivan Kostov is Professor at the University of Sofia, Member of the Bulgarian Academy of Sciences, Director of the Geological Institute of the Bulgarian Academy of Sciences, and of the National Natural History Museum. He is a well-known specialist in mineralogy, has numerous publications on crystal chemistry, morphology, genesis and systematics of minerals, a widely circulated textbook of mineralogy translated and published by Oliver & Boyd, England, and by the Mir Publishing House, USSR, and a textbook of crystallography translated and published in the USSR. Together with associates (one of them the co-author) he published the book Minerals of Bulgaria, at present the only comprehensive such book for that country. He is honorary member of many mineralogical and geological societies and member of "Leopoldina."
Jordanka Minceva-Stefanova is Professor, Head of the Section of Mineralogy at the Geological Institute of the Bulgarian Academy of Sciences. She is a leading specialist in sulphide mineralogy, with numerous publications on strata-bound sulphide ores in Bulgaria and adjacent countries, and on problems of isomorphic substitution, crystal morphology and mineral genesis. She is national representative in the IMA Commission on Ore Microscopy. Together with other colleagues she worked out The Mineralogical Dictionary of the Carpatho-Balkan Region.