What term is used for the soft, diamond-bearing material found near the surface of diamond fields?

The term "Yellowground" refers to the soft, diamond-bearing material that is typically found near the surface of diamond fields. This material is significant in diamond mining, as it often contains diamonds that have weathered out of their primary sources and accumulated in secondary deposits. The name "Yellowground" can vary regionally but usually describes sedimentary layers rich in mineral content, including diamonds.

The other options, while related to materials found in various contexts, do not specifically describe the soft, diamond-bearing layer as accurately. Diamond paste is generally used in polishing diamonds rather than being a source of naturally occurring diamonds. Glacial till refers to the unsorted debris deposited by glacial action, which generally does not directly relate to concentrated diamond deposits. Topsoil, on the other hand, is the uppermost layer of soil that supports plant life but does not specifically indicate the presence of diamonds. Thus, Yellowground is the most precise term for the context of diamond-bearing materials.