Ore study of economic geology, or ore genesis. The classifications below are typical. The basic extraction of ore deposits follows these steps: Ores (metals) are traded internationally and comprise a sizeable portion of international trade in raw materials both in value and volume. This is because the worldwide distribution of ores is unequal and dislocated from locations of peak demand and from smelting infrastructure. Most base metals (copper, lead, zinc, nickel) are traded internationally on the London Metal Exchange, with smaller stockpiles and metals exchanges monitored by the COMEX and NYMEX exchanges in the United States and the Shanghai Futures Exchange
Ore condition condition ensures "R" is an essential submodule of "D". Lastly, there is even an example of a domain in a division ring which satisfies "neither" Ore condition (see examples below). Another natural question is: "When is a subring of a division ring right Ore?" One characterization is that a subring "R" of a division ring "D" is a right Ore domain if and only if "D" is a flat left "R"-module . A different, stronger version of the Ore conditions is usually given for the case where "R" is not a domain, namely that there should be a common multiple