You must realize that the Earth provides us with all the raw materials swallowed up by our industries. Many of these material are minerals. The word ‘mineral’ is used to denote any substance obtained by mining. It is clear that the words mine and mineral have similar origins. You might expect that Minerals would be spread throughout the Earth, and indeed, this does happen. Occasionally, however, minerals may accumulate in sufficient quantities for man to be able to remove them comparatively easily. When this situation arisese, the deposits are usually known as ores or ore bodies. The minerals associated with the ores that have no real economic value are usually referred to as gangue minerals. Today, because of the greater demand for minerals. Today, because of the greater demand for minerals, the consequent scarcity of them, and improved methods of mining and refining, material that was once thrown on the spoil heaps can now provide valuable sources.
Ores can occur in a variety of ways. With ores or iron, for example, the same ore can arise as a result of different methods of concentration. Many ores other than iron are formed in association with magmatic processes. If you remember the way in which a magma cools and forms crystals, it will come as no surprise to you to learn that metals such as chromium and nickle result from the settling into bands of the relevant crystals as the magma cools. There are often watery solution charged with minerals coming from magmas and these also provide supplies of metals such as mercury or copper. Both these minerals are in short supply, and in fact, deposits of mercury are almost completely confined to areas in Spain.
Not all ores have been formed by igneous activity, however. Important deposits of iron in England have resulted from concentration by sedimentary process. Deposits known as placers are typical sedimentary ores. Of course, oil and coal must be considered as economic minerals and these have obviously resulted from sedimentation.
The sea may one day provide much of the world’s minerals. It has been known for some time that there is great richness of gold in the sea but as yet it has not been worthwhile nor even possible to exploit this mineral wealth. Even uncommon metals like vanadium, which is used for the nosecones of spacecraft, is concentrated in the blood of an unexciting sea animal the sea cucumber.