Gold

Crystal system: Department of equiaxed grains 
Chemical composition: Au 
Characteristics: hardness 2.5 to 3, the proportion of 19.3. Metallic luster, opaque, color and streak are yellow. Acid, but dissolved in aqua regia, the chemical is very stable metal. Never been in the air oxidation, the extension of special and is also an excellent electrical and thermal conductor. 
Occurrence: mainly in quartz veins, paragenetic minerals has limonite, pyrite, stibnite, sphalerite and arsenopyrite are also dispersed in the quartz andesite, granite, sandstone and conglomerate in. 
Purposes: the International Monetary Fund, casting money, jewelry, precious stones inlaid. Industry for the gold-plated, printed circuit board assembly line of the joints, manufacturing alloys, electrical and electronic semiconductor materials is important.