Overburden Drilling Management indicator mineral processing. . The grain separation procedure corresponds to the standard ODM flow chart. Concentrates are picked for 4 main indicator minerals; pyrope, ilmente, chrome diopside and chromite. Due to the abundant kimberlite indicator mineral content in the 4 kimberlite samples, only ¼ to 1/16 of the samples are picked. Grain identities are not confirmed by electron microprobe.