EXPERIMENTAL INVESTIGATION OF THALLIUM SULFOSALT SYSTEMS AND THEIR CORRELATION TO NATURAL ASSEMBLAGES - A RETROSPECT TO ALLCHAR

The low concentrations of thallium in polymetallic ore deposits of low temperature hydrothermal origin did not permit an easy extraction of the toxic Tl minerals and their crystal-chemical determination. Experi mental petrology is the most suitable method to determine experimental ly, under defined physico-chemical conditions within the chosen hetero geneous system represented as a phase diagram, the properties of Tl-su lphosalts, and as well chemistry and geochemistry of this element. The se investigations occurred to be particularly recommendable in determi nation of complex assemblages and equilibria between the Tl phases. Tl has a very high affinity to sulphur and it should be possible to make use out of this property in order to extract Tl sulphides or sulphosa lts either during mineral processing or ore mineral dressing procedure s. Besides sulphur, arsenic and antimony as essential elements found i n Tl sulphosalts, silver is another element often found therein. Due t o its presence in Allchar and in order better to understand the phase relations within Tl sulphosalt systems we have investigated Ag2S-Tl2S- AS(2)S(3)-Sb2S3 system and its sub-systems.