What is an ore?
Ore is defined as an economic concentration of minerals. The richness of ores can be vastly different, depending on the minerals and elements involved. Chromium ore consists mainly of the mineral chromite, of which chromium is a major constituent. Most vanadium ores are made of magnetite, but vanadium is only a minor element of that mineral. Platinum ore contains only traces of platinum-rich minerals, and most of them are so tiny that they cannot be seen by the naked eye.
The chromium ore contains 25 percent chromium, the vanadium ore 2 percent vanadium, and the platinum ore 0.0008 percent platinum and related elements.
Layers of chromite (black) are found near the bottoms of some magma chambers and are a source for the element chromium.
This rock is composed almost entirely of the iron oxide mineral magnetite, so named because it is naturally magnetic.
About 75 percent of the world’s platinum is mined from the Merensky Reef — a layer, usually only a few tens of centimeters thick, in the Bushveld Complex.