Which minerals are commonly used as indicators in diamond exploration such as black spinels and red garnets?

• A. Indicator minerals
• B. Character sample
• C. Bulk sample
• D. Drift

Answer: (A)

Indicator minerals are the minerals used to point toward diamond-bearing rocks. Black spinel and red garnet are classic examples because they form in mantle rocks that are associated with kimberlite, the primary carrier of diamonds, and they survive weathering and transport to surface or near-surface deposits. When these minerals appear together in heavy mineral concentrates, till, or river sediments, they guide geologists toward the likely source pipe and help focus follow-up exploration and drilling. The other terms describe sampling methods or materials rather than the minerals themselves: a character sample isn’t a standard term for guiding exploration, bulk sampling is about testing ore content in a deposit, and drift refers to glacial sediments that can carry indicators but isn’t the mineral category itself.