Minerals are solid substances formed naturally through geological processes. They are defined by their chemical composition, colour, and crystal structure. These characteristics help in determining their industrial uses and classification.
Most minerals have a regular crystalline structure. The internal arrangement of atoms in a crystal is called the crystal lattice. Some mineral formations occur when rocks are exposed to high temperatures.
A mineral can also have an external form. This form could be a crystalline rock such as granite or a sedimentary rock such as sandstone. When a mineral grows, it usually develops into a well-developed crystal.
Some minerals display a variety of colours due to impurities. For example, diamond is a mineral made of carbon. Diamond is also the hardest mineral.
Another common property of a mineral is luster. Luster refers to the reflection of light off a mineral. It is described as shiny, glassy, metallic, or dull.
One of the most important physical properties is specific gravity. Specific gravity is the density of a mineral relative to water. Water has a specific gravity of one.
Cleavage is another characteristic of minerals. Cleavage is a process by which a mineral breaks into small cubes. Quartz, for instance, has conchoidal fractures.
Other common properties of minerals include hardness, color, and diaphaneity. Hardness can be measured by scratching the mineral against a standard object. Color is often used to describe a mineral, but it should not be relied upon for identification.