Mineral inclusions in magnetite as a guide to exploration - preliminary results

Mineral inclusions are a common feature in magnetite and can be used to discriminate between barren and mineralized host rocks. Common inclusion types from barren host rocks include silicate phases (e.g. feldspars, mica, sericite, chlorite), apatite, zircon, and rutile reflecting the host rock's mineral assemblage. Magnetite in mineralized rocks often has inclusions of minerals that are directly associated with mineralization such as sulphides or other ore-related mineral phases. Chalcopyrite and pyrite inclusions in magnetite are indicative of porphyry-style sulphide mineralization from porphyry Cu (Mo) and associated skarn deposits in the western United States. Mineral inclusions in magnetite can be preserved through a range of geologic processes that would otherwise breakdown or alter the included mineral phase. In combination with minor and trace element compositions of the host grains, inclusions can provide useful genetic information and be a powerful asset for exploration using heavy mineral concentrates.