Gold is extremely resistant to weathering

Gold is extremely resistant to weathering and, when
freed from enclosing rocks, is carried downstream as
metallic particles consisting of “dust,” flakes, grains,
or nuggets. Gold particles in stream deposits are often
concentrated on or near bedrock, because they move
downward during high-water periods when the entire
bed load of sand, gravel, and boulders is agitated and
is moving downstream. Fine gold particles collect in
depressions or in pockets in sand and gravel bars
where the stream current slackens. Concentrations of
gold in gravel are called “pay streaks.”