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
Volcanogenic massive sulfide ore deposit sulfide consists of over 90% iron sulfide, mainly in the form of pyrite, with chalcopyrite, sphalerite and galena also being major constituents. Magnetite is present in minor amounts; as magnetite content increases, the ores grade into massive oxide deposits. The gangue (the uneconomic waste material) is mainly quartz and pyrite or pyrrhotite. Due to the high density of the deposits some have marked gravity anomalies (Neves-Corvo, Portugal) which is of use in exploration. Alteration haloes developed by VMS deposits are typically conical in shape, occur mostly stratigraphically below the original fluid flow location (not necessarily the ore itself), and are