Ore deposits are classified according to various criteria developed via the study of economic geology, or ore genesis. The classifications below are typical.

Magnified view of banded iron formation specimen from Upper Michigan. Scale bar is 5.0 mm.

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.

Iron ore is traded between customer and producer, though various benchmark prices are set quarterly between the major mining conglomerates and the major consumers, and this sets the stage for smaller participants.