Placer Deposits

Under construction

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