Geology of Indium Deposits-a Review

Abstract

The indium-bearing deposits in the world were reviewd from the geological point of view. This research revealed that the following factors are important for indium concentration in nature, from large-scaled order to smaller one; (1) acid magmatism; (2) ilmenite-series granite; (3) a region in a ilmenite-series district which is established based on the concept of segment; (4) hydrothermal tin-polymetallic deposits (n×10 ² -10 ³ ppm In) and volcano-sedimentary deposits in the continental crust (n×10 ppm In); (5) cauldron for some of the tin-polymetallic deposits; (6) subvolcanic to plutonic condition for tin-polymetallic deposits; (7) certain zone in a tin-polymetallic mine where cassiterite and sulfides (especially bornite) coexist. The geochemical behavior on indium in volcano-sedimentary deposits are not well understood, thus, geologists should study indium of this type of ore, e.g., the specimen from the Kuroko and also from the Okinawa Trough in addition to the research on tin-polymetallic deposits.