Most diamonds mined today originate from which type of deposit?

• A. Secondary Deposits
• B. Alluvial Deposits
• C. Surface Deposits
• D. Primary Deposits

Answer: (D)

Diamonds form deep in the mantle and are carried to the surface by explosive kimberlite magma, creating primary deposits such as kimberlite pipes or dikes where diamonds are native to the rock. Over time, weathering can release diamonds from these rocks and they are then carried and concentrated in riverbeds or coastal sands as secondary (alluvial) deposits. While alluvial deposits are economically important and can be substantial, the diamonds that miners extract most directly come from the primary host rock, where the diamonds are embedded in solid ore. So, the best answer reflects that the original source of most mined diamonds is the primary deposits rather than secondary deposits.