All known deposits were exhausted hundreds of years ago.
Iron resources in known deposits total 2200 million metric tons of ore.
Lightning Ridge has the largest known deposits of black opals in the world.
Further, the area contains the only known deposits of llanite.
By the early 1840s, most of the "easy" gold had been found, and efforts began to shift to working the known deposits.
Nearly all the known deposits were located in the United States, and the market demand was high.
Belgium and Canada have the greatest known deposits of uranium.
About half of all the known deposits are under exploitation.
Zimbabwe has 30 billion tons of coal in 21 known deposits.
Since 2002 there has been a new surge in exploration, driven mainly by small companies focused on proving known deposits.
