Quartz vein with pyrite and gold being weathered and formation of residual and eluvial placers.
Concentration of gold and heavy minerals often occur at the following places: (1) sudden drop-off into deeper and larger volume of water; (2) in cracks/crevices in stream bed; (3) behind rock bars or outcrop of harder rocks across the stream; (4) in pot holes/rock holes; (5) downstream from tributary; (6) when stream channels widens; (7) behind large boulders and riffles (obstructs); (8) behind islands; (9) where the slope of the stream becomes less; (10) behind sharp curves where the water bounces several times against the banks; and (11) at gravel bars (point bars) that form at the inside banks of meander loops.
Concentration principle 1: Sudden drop-off into deeper and larger volume of water where the flow velocity is less than upstream.
Concentration principle 2: Gold is deposited in crevices, cracks, joints or fractures in stream bed.
Concentration principle 3a: Gold is deposited were the stream bed exhibits natural riffles and rock bars, i.e. resistant beds, dykes or veins.
Concentration principle 3b: Were obstructions are in stream bed and prevent the stream flow, the concentrating effects of eddies are of importance.
Concentration principle 5:
downstream from tributary
Concentration principle 7: behind large boulders
Concentration principle 9: When stream channel widens