Native, radioactive, and sulfide mineralization at the Botogol'skoe graphite deposit (East Sayan)

This paper presents the results of the first study of the native, radioacti ve, and sulfide mineralization at the Botogol'skoe graphite deposit (East S ayan) known for more than 150 years by its high-quality graphite of magmati c genesis. Native mineralization in graphite is crystalline silicon, native iron, and gold, which, in association with moissanite, permit one to refin e the conditions of the graphite formation and to corroborate the hypothesi s for the deposit formation at the magmatic stage of alkali intrusion with the active participation of the gas phase. Radioactive mineralization is lo cally abundant at the deposit as uraniothorianite in graphite and as monazi te and fluorite in fenites and fenitized marbleized limestones. The authors have studied the gold and platinum potentials of graphites and host nepheline syenites and sulfide ores which form nests in alkali rocks a nd are made up of pyrrhotite with the subordinate quantities of chalcopyrit e, arsenopyrite, sphalerite, and marcasite. The presence of low-grade gold, hessite, and sperrylite in the sulfides and graphite indicates possible pa rticipation of noble (and other native) metals in the formation of the alka li intrusions and graphitic ores. The specific features of the massif and g raphite deposit is that their origin is caused by assimilation of bituminou s limestones in the apical part of the high-temperature syenitic magma simu ltaneously with ifs desilication and alkalization and release of large amou nts of reduced gases.