You encounter minerals every day, from the quartz inside your watch to the gemstones you wear on your fingers, and yet you may not realize the abundant nature of minerals on Earth. Thousands of minerals have been discovered, but only about 200 are common to the average person. Humans cannot live without minerals; they keep the human body functioning normally. People use minerals every day within their bodies and in many industries, but minerals cannot be made by man.
Minerals must be found occurring naturally. Substances concocted in laboratories cannot be considered minerals because they don't exist in nature. Although some laboratory products resemble minerals, they are not true minerals. Cubic zirconia and synthetic corundum, a substance passed off as a ruby or sapphire in high school graduation rings, are not true minerals because even though they conform to the other characteristics of minerals, they do not occur in nature. Not all naturally occurring substances are crystals either; opal and amber, the sap of ancient trees that have fossilized, are not minerals. Substances called mineraloids may look like minerals but are not because they don't satisfy all the requirements of minerals.
Minerals are not organic, meaning they don't belong to any class of organic compounds. Organic compounds comprise substances such as carbohydrates, proteins and fats made by living things. Almost all known minerals come from inorganic processes -- activities that living things cannot carry out. A few minerals such as pearls and the shells of some creatures do originate from organic processes. All organic substances contain carbon, but inorganic substances also can contain carbon; however, in inorganic substances, the carbon typically bonds with elements other than hydrogen and does not form long chains as it does in carbohydrates and fats.
Minerals cannot be liquids or gases; they exist only as solids, a state of matter that possesses a high amount of order. Ions, charged atoms, bond together to form minerals. This formation gives minerals a solid structure. Solids have a clearly defined volume and shape, and their molecules normally cannot be compressed any further. Their structures are rigid, meaning that the particles within the mineral don't move around. Solids can be crystalline or amorphous. Crystalline solids such as minerals have repeating patterns whereas amorphous solids such as glass do not.
Definite Chemical Composition
Each mineral has its own specific combination of atoms that cannot be found in any other mineral. Atoms in minerals bind together to form compounds. Salt is a mineral; it forms crystals, and these crystals contain sodium and chlorine ions bonded together in a repeating pattern. Diamonds, on the other hand, have only one type of atom: carbon; these carbon atoms come together extremely tightly in a type of chemical bond different from the one responsible for forming salt, making diamonds the hardest substance on Earth. Some minerals such as gold, silver, copper and diamonds have only one type of element in them. The largest group of minerals contains some form of silicate, a combination of silicon and oxygen atoms.
Minerals have crystals that contain repeated arrangements of atoms or ions; each repeating part of a crystal is a unit cell. The unit cell can have different shapes because of the size of the ion or atom and how it attracts other particles. Crystals usually take one of six common shapes, including cubic and prism forms, although other forms exist less commonly. Minerals have crystalline structures that are formed in two ways. Magma or lava, the hot, molten rock that comes from volcanoes, can become crystallized to form minerals. Minerals crystallize also by the action of water when oceans or seas deposit substances dissolved in them in a certain area; when the water has evaporated, crystals appear.