The word Alluvial describes a type of soil. It can be made up of sand, silt, clay, gravel, or other matter deposited by flowing water.

The term "Alluvial Gold" specifically refers to gold dust found in that type of soil. When riverbed soil is scooped up and panned for gold dust, that ist alluvial gold.

Alluvium (from the Latin, alluvius, from alluere, "to wash against") is soil or sediments deposited by a river or other running water. Alluvium is typically made up of a variety of materials, including fine particles of silt and clay and larger particles of sand and gravel.

Gold nuggets and particles which are found in rivers and streams and are recovered by dredging or panning methods...:/