Placer mining, hard rock mining, byproduct mining and by processing gold ore.
In placer gold mining, the gold is retrieved by metal detecting, panning, cradling, sluicing and dredging. Using gravity and water to separate the dense gold from the other materials that surround it, this is the most common gold mining category for amateur gold hunters.
Hard rock gold mining is the process of using open pit or underground mining tunnels to retrieve the gold from the rock. This method of gold mining is responsible for recovering most of the worlds gold supply.
Byproduct gold mining is related to hard rock mining in that open pit or underground mining tunnels are used. In byproduct mining, gold is a secondary find. The main purpose of the mining operation is the recovery of Copper, sand, gravel or other products but significant quantities of Gold exist to make byproduct mining a profitable venture. An example of this kind of mining would be the Grasberg mine is Papua, Indonesia, which was developed for extracting Copper from the earth. Though Gold is not the primary product, this mine produces more Gold than any other mine in the world.
The final category of gold mining is the leaching processing of Gold ore. This method is largely becoming deprecated as the yield of Gold is often very low and the environmental impact and costs of the operation are substantial. The Gold ore is finely crushed rock or earth containing trace amounts of Gold which are extracted using a chemical process. The most commonly used chemical for this process is Sodium Cyanide.