Gold is most often found in very small amounts mixed with other materials. Experienced gold prospectors rarely look for gold, but rather look for rocks and rock formations that are known to hold gold.
Gold is most often found in quartz rock. When quartz is found in gold bearings areas, it is possible that gold will be found as well. Quartz may be found as small stones in river beds or in large seams in hillsides. The white color of quartz makes it easy to spot in many environments.
Alluvium is a deposit of eroded materials and sediment that is gathered into one area. As gold and other materials are eroded, the small pieces are pushed by water and other forces into creek and river beds and other depressions. Because gold is heavier than most other naturally occurring materials, it settles at the bottom of these deposits.
Intrusive rock is formed when molten magma is pushed between layers of existing rock. Intrusive rock is typically very hard and erodes slowly. This allows the surrounding rock to be worn away by wind and water, leaving only the harder rock in place. Heavy particles, such as gold, are likely to accumulate against the harder rock while the lighter materials are more easily moved away.