Primary diamond deposits are found inside which geological structures?

• A. Found in rock that carried them to surface
• B. Inside lamproite and kimberlite pipes
• C. Alluvial and marine
• D. Rivers & streams

Answer: (B)

Diamonds form deep in the mantle and are transported to the surface by volatile-rich magmas that crystallize into pipes. These pipes, known as kimberlite and lamproite pipes, are the primary host rocks that carry diamonds from depth to shallow crust, preserving the diamonds inside. That’s why primary diamond deposits are found inside kimberlite and lamproite pipes. In contrast, alluvial and marine deposits arise from weathering and erosion of these primary sources, concentrating diamonds in riverbeds, beaches, or seabeds rather than hosting them as primary rocks. Rivers and streams specifically are typical settings for such secondary placers.