Which group of minerals signals potential diamond-bearing rock when found in the area?

• A. Open pit
• B. Bulk sample
• C. Micro diamond testing
• D. Indicator minerals

Answer: (D)

Indicator minerals are minerals that commonly accompany diamond-bearing rocks, such as kimberlites. Finding them in a region—often in heavy-mineral concentrates from till, stream sediments, or soil—signals a nearby potential diamond source because these minerals form and travel with the same geological processes that bring diamonds to the surface. In exploration, the presence of a suite of indicators like pyrope garnet, chromian diopside, chromite, and ilmenite suggests kimberlite proximity and the possibility of diamonds, guiding follow-up drilling and sampling. The other choices describe mining or testing methods rather than mineral groups, so they don’t serve as the field signal that points to a diamond-bearing rock.