A mineral resource is the concentration of materials that are of economic interest in or on the crust of the Earth. Almost all minerals found on Earth are used in one way or another for economic benefit. Examples of minerals include gold, gravel, sand, aluminum, copper, limestone, clay and diamond.
Finding and exploiting mineral resources often requires machinery. Some minerals, such as sand, clay and gravel, are unrefined and used as they are found. Most minerals, such as iron and aluminum, must be processed before they can be used. Metals are used to make machines, diamonds are frequently used in making jewelry, and sand is used in building foundations.