Which type of deposit has a higher concentration of diamonds?

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

Answer: (C)

Diamonds are very dense and resistant to weathering, so once they’re released from their primary host rocks, they tend to accumulate where the overlying sediments and moving water can sort and deposit them. Near the surface, heavy minerals like diamonds are efficiently separated from lighter material by gravity and water flow, forming placer-like concentrations in surface sediments. These unconsolidated, near-surface sediments can show higher local diamond concentrations because the sorting processes have already concentrated the diamonds into relatively small, workable pockets. In contrast, primary deposits trap diamonds within the rock matrix and often require more extensive mining to access the same quantity, and other secondary settings can be more dispersed. This is why surface sediments are typically the type with higher concentration of diamonds.