Deposits Formed by Sedimentary and Surficial Processes - Metals and Society: An Introduction to Economic Geology - page 118

Box 5.1 The Great Gold Rushes of the Nineteenth Century
Free gold, the term used to describe separate particles of native (elemental)
gold in stream beds, is readily extracted by miners using simple methods such
as the gold pan or sluice box (a simple wooden frame over which a slurry of
gold-bearing gravel and sand is allowed to flow - ridges or mats on the floor of
the box collect the particles of gold). Deposits of alluvial or placer gold were
mined by many primitive societies, including the Romans who for two
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