Minerals are what the Earth’s rocks are made of. A mineral is a natural solid substance with a particular chemical composition and an individual core crystal structure. Minerals are usually formed by inorganic developments, although there are other minerals that are produced organically such as hydroxyl apatite in teeth and bones. Some substances such as opal and glass resemble minerals in chemistry and occurrence, but they do not have a regularly ordered internal arrangement. These are known as mineraloids.
Most minerals are chemical compounds composing of two or more chemical elements. However, copper, sulphur, gold, silver and a few others occur as single native elements. A mineral is classified by its chemical formula and by the atomic arrangement of its crystallisation.
There are more than 4,000 known minerals, but only about 100 of these are common.
Silicates such as quartz, feldspar and olivine are by far the most common minerals in
rocks, making up about 90 percent of the rocks at the Earth’s surface. Carbonates are
essential in forming sedimentary rocks such as limestone. Sulphides such as pyrite and
galena, and oxides such as hematite, are also relatively common, as are native
elements such as copper.
The term mineral is commonly applied to certain organic substances such as coal, oil,
and natural gas. But these ought to be referred to as hydrocarbons. Gases and liquids
are not minerals. Synthetic equivalents of certain minerals, such as emerald and
diamonds, are not minerals because they were not naturally developed. The
“minerals” in food are also not minerals in the geological sense as they refer to single
elements like zinc, iron or calcium.