On the earth, gold is a kind of heavy metal with little content but widely distributed. The initial reason for the formation of gold deposits is geological movement, which gradually increases the abundance of gold in some strata. Then, through the action of volcanoes and earthquakes, the specific gravity of Jin Yanshi is further enriched and rises to the outcrop. Humans first discovered gold from outcrop gold mines and used it.
Extended data:
Prospecting method of placer gold;
1. The main ore body has simple shape, large scale, stable thickness, uneven distribution of placer gold, flat bottom and small slope. Most large flood plain placer gold deposits and coastal placer gold deposits belong to this type. For example, Hengkou River alluvial plain gold mine in Shaanxi Province and Dalahan River alluvial plain gold mine in Heilongjiang Province.
2. The main ore body has simple shape, medium extension scale, little change in thickness, uneven distribution of placer gold, uneven floor and large gold particles and nodular minerals. Most of the flood plain gold deposits, large branch valley gold deposits and terrace gold deposits with flat floor or karst basement belong to this type. Such as Xinglonggou placer gold mine in Heilongjiang Province.
3. The ore body is small in scale, complex in shape, with great thickness variation, uneven floor dip angle and extremely uneven placer gold distribution. There are more large-grained gold, more syngenetic gold and diamond minerals. Small-scale leaching type, slope type, flood type and branched karst filling type gold deposits mostly belong to this type of gold deposits. Such as the residual slope placer gold deposit in Xicaiyuan, Inner Mongolia Autonomous Region.
References:
Baidu encyclopedia-placer gold