Formation conditions of high-grade beryllium ore at the Snezhnoe deposit, Eastern Sayan

摘要

The structure and formation conditions of beryllium ore, as well as the fluorite and fluorite-microcline bodies at the Snezhnoe deposit in Eastern Sayan have been revealed and studied using geological, mineralogical, petrographic, and thermobarogeochemical methods. It has been established that the stringer and breccia ores were largely formed as a result of filling of open cavities (voids and fissures) rather than of replacement of low-Ca host rocks. Three types of high-grade ore consist of almost the same set of minerals in different proportions. Calcium and fluorine necessary for fluorite formation in three main types of ore have been supplied with the near-neutral high-F solutions (type I) and the solutions of elevated alkalinity (II, III types) in the form of complex compounds like Na2CaF (4) (0) , Ca2Cl3F0, etc. Beryllium minerals were deposited within a temperature interval from a parts per thousand yen340 to 230A degrees C due to the cooling of the solution and binding of F into fluorite with the breakdown of Be fluorine complexes and intense deposition of Be minerals.