The jacobsite-magnetite series at the Tumurtijn-ovoo Fe-Mn-Zn skarn deposit, Mongolia

摘要

Members of the jacobsite-magnetite series (Mn-Fe spinels) are main constituents of the andradite-skarn body which contains the rich submarine hydrothermal sphalerite mineralization at Tumurtijn-ovoo in Eastern Mongolia. They have been investigated by microscopy, X-ray diffractometry and electron microprobe analysis. Their composition varies along the whole join between ideal jacobsite (MnFe2O4) and pure magnetite (FeFe2O4). A correlation is found between Mn2+-Fe2+ proportions and lattice constants. Whereas magnetites occur in the whole skarn body, Mn-rich species (jacobsite and manganoan magnetite) are limited to the Zn-rich lithostratographic Upper Skarn Unit.