Mainly refers to the precious metals gold (Au), silver (Ag) and platinum, palladium (Palladium) and other expensive metals, in addition to industrial uses (including jewelery), the value of the investment and also has its own preservation. Precious metals such as gold mineral exploration more difficult than other non-precious metal is high, the mineralized crystal is much finer than other metals reserves in the world is also much lower than other metals, so the formation of its precious status.