Indium demand has increased due to the production of cell phone screens, solar cells, alloys, and LED displays. This suggests a need for increased exploration, which can aide in constraining where in space and time indium-bearing deposits are likely to form. Exploration vectors are suggested based on results of experiments conducted on the partitioning behavior of indium between ferromagnesian (biotite and amphibole), a felsic melt, and vapor phases. D_In^(Bt/Melt) ranges from 0.6 ± 0.1 (1 σm) to 16 ± 3 (1 σm) and is a function of the biotite composition, with D_In^(Bt/Melt) decreasing with increasing X_Annite^Bt. D_In^(Am/Melt) is 36 ± 4 (1σm) and D_In^(Vapor/Melt) is ~17 ± 5 (1σm). Exploration vectors suggest that granites that lack amphibole and contain iron-rich biotite have a higher potential to be associated with indium-bearing deposits.