Coal is very different from mineral rocks, which are made of inorganic material. Coal is made of fragile plant matter, and undergoes many changes before it becomes the familiar black and shiny substance burned as fuel.
Petroleum is found in vast underground reservoirs where ancient seas were located. Petroleum reservoirs can be found beneath land or the ocean floor. Their crude oil is extracted with giant drilling machines.
There are several processes for refining iron from ore. The older process is to burn iron ore with charcoal (carbon) and oxygen provided by bellows. The carbon and oxygen, including the oxygen in the ore, combine and leave the iron.
Base metals refers to industrial non-ferrous metals excluding precious metals. These include copper, lead, nickel and zinc.
A Transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. A varying current in one coil of the transformer produces a varying magnetic field
