Minerals are elements and compounds. Minerals have definite chemical compositions and physical properties. Some common minerals are feldspar, quartz, calcite, mica, and hornblend. Some minerals are valuable enough to be mined. Some of theses are the metal ores from which we obtain iron, lead, copper, aluminum, zinc, gold, and silver.
Minerals make different rocks look different.
A granite rock, for example, has different minerals than a basalt rock. However, even rocks with the same minerals may look different due to variations in the relative amounts of minerals and the processes by which they are formed. Some rocks may contain minerals in the form of crystals. Crystals have a regular geometric shape. There are 6 basic crystal shapes.