African diamonds can be recovered from which types of deposits?

The correct answer identifies the types of deposits where African diamonds can be recovered, specifically highlighting pipe, alluvial, and marine deposits.

Pipe deposits refer to kimberlite pipes, where diamonds form deep within the Earth's mantle and are brought to the surface through volcanic activity. These are considered primary deposits and are significant sources of diamonds. Alluvial deposits are formed when diamonds are weathered out of their primary sources and transported by water, settling in riverbeds, beaches, or ocean floors, which is a common method of recovery in diamond mining. Marine deposits involve diamonds that have been transported by rivers to the ocean, where they accumulate on the seabed, creating opportunities for underwater mining.

This combination reflects the diverse geological processes that can lead to the formation and recovery of diamonds in Africa, making them not only valuable but also a testament to various natural processes contributing to their deposit.