In this topic you will learn about how minerals are used in different ways.

What do diamond rings, talcum powder, and aluminum foil have in common? They are made of minerals. A mineral is a solid material of Earth's crust with a definite composition. Like all matter they are made of elements. Some minerals, like gold, silver, and copper are made of one element. Most minerals are made of compounds.

No two minerals are exactly alike. Each has its own set of properties that you can use to tell it apart. Luster is the way light bounces off a mineral. Minerals with a metallic luster are shiny. Streak is the color of the powders left when a mineral is rubbed against a hard, rough surface. The streak is always the same for a given mineral, even if the mineral varies in color. The streak may not be the color of the outer surface of the mineral.

Hardness is a measure of how well a mineral resists scratching. Soft minerals are easily scratched. Moh's hardness scale is a numbered list of minerals. Talc, number 1, is the softest mineral. It can be scratched with your fingernail.

The way a mineral breaks is also helpful. Some minerals have cleavage, the tendency of a mineral to break along flat surfaces. Cleavage is described by the number of directions, or planes, the mineral breaks in. Many minerals do not break smoothly. They are said to have fracture.

Some of the most useful minerals are ores. An ore is a mineral that contains a useful substance. Ores contain enough useful substances to make it valuable to mine them. For example, iron comes from the mineral hematite. Aluminum comes from the mineral bauxite. The iron and aluminum that come from these two ores are metals. Metals have many useful properties.

If you look in a jewelry store window, you will probably see some minerals called gems. A gem is a mineral valued for being rare and beautiful. Diamonds, rubies, and sapphires are gemstones.

Earth's supply of minerals is being used up. Minerals are nonrenewable resources. A nonrenewable resource cannot be replaced within a short period of time or at all. Because minerals are nonrenewable they must be conserved. To conserve means to use wisely or avoid waste. One way people can conserve minerals is by recycling them—finding ways to treat them and use them again.