Minerals

Minerals are substances that are formed naturally in the Earth.

The study of minerals is called mineralogy.

Characteristics of minerals

Rocks and minerals are formed in nature, but they are different in that a rock is made up of multiple minerals. Below you’ll read about what makes a mineral.

Physical Properties

A mineral is a solid—that is, it has a definite volume and a rough shape.

A substance that is a liquid or a gas is not a mineral. However, in some cases its solid form is a mineral. For instance, liquid water is not a mineral, but ice is.

Crystal structure

The particles of ice that make up frost have smooth, flat surfaces. These flat surfaces form because of the arrangement of atoms in the ice, which is a mineral. Such an arrangement is a characteristic of minerals. It is the structure of a crystal, a solid in which the atoms are arranged in an orderly, repeating 3D pattern.

Each mineral has its own type of crystal structure. In nature, a perfect crystal is rare. Most crystals have imperfect shapes because their growth was limited by other crystals forming next to them.

Chemical properties

Each mineral has a definite chemical makeup: it consists of a specific combination of atoms of certain elements. An element is a substance that contains only one type of atom.

Scientists can classify minerals into groups on the basis of their chemical makeup. Though there are thousands of different minerals, only about 30 are common in Earth’s crust. Since these 30 minerals make up most rocks in the crust, they are called rock-forming minerals.

  • Silicates are most common group. All the minerals in this group contain oxygen and silicon—the two most common elements in Earth’s crust—joined together. This includes calcium, iron, and quartz.
  • Carbonates are the second most common group of rock-forming minerals. All the minerals in this group contain carbon and oxygen joined together. Calcite, which is common in seashells, is a carbonate mineral.
  • Oxides include the minerals from which most metals, such as tin and copper, are refined.
  • Sulphates commonly form where highly salty waters slowly evaporate. Sulphates also occur where hot waters are forced through the rock, as with geysers.

There are many other mineral groups.

Some uses of minerals

  • Graphite is used to make pencils.
  • Rock salt is used in cooking.
  • Mineral are the source of metals.
  • The copper in wires that carries your electricity is made from a mineral.

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