| Annotation |
The relevance lies in the need to have objective data to assess the belonging of pyrite outcrops to the day surface to the supra-ore zones of gold deposits of a shallow gold-silver formation based on objective data on its chemical composition and forms of crystals and their aggregates. The purpose of the study is to determine the chemical composition of pyrite, the forms of its crystals and aggregates as typomorphic signs of their belonging to the supra-ore zone of the deposit of this formation. The object of the research is pyrite of the supra-ore zone of the Taseevskoye deposit, which is unique in terms of gold content and reserves. The subject of the research is the chemical composition and forms of pyrite separation. The method and methodology are presented by optical and electron microscopy with the determination of variations in the chemical composition of pyrite and morphological features of crystals and their aggregates.
Results. The determination of the chemical composition of pyrite was carried out and it was found that almost all crystals are characterized by a sulfur deficiency, the formula coefficients of which are 1.801–1.939 with a change in content from 48.39 to 52.62 %. In 70 % of the measured pyrite crystals, arsenic is present from 0.72 to 4.78 % the formula coefficients of which are 0.007 - 0.076. In 2 % of pyrite crystals, along with As, antimony was found in an amount of 0.21 - 0.71 %, formula coefficients are 0.006 - 0.007. The forms of pyrite crystals are cubic, cubopentagondodecahedral, rarely cuboctahedral and subspherical aggregates, less often lenticular and veinlet, predominate.
Conclusions. For the first time, original data on the chemical composition of pyrite in the supra-ore zone of the Taseevskoe gold-silver deposit were obtained. It is shown that its feature is high arsenic content (0.72 - 4.78 %), which can be an important typochemical sign for determining the belonging of chalcedony-like quartz containing it to the supra-ore zone of a shallow gold-silver formation |
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