.....Minerals, especially gems and precious metals, are among the oldest objects used and treasured by society. Today our industrial economy relies extensively upon the metals extracted from many minerals. For example, the metal iron is refined from the mineral hematite (iron oxide), using a heating process to separate the iron from the oxygen. In addition to the minerals that contain metals, many others are also useful to society. An example would be the mineral gypsum, used for making drywall and wallboard. The Table to the right, lists a few of the minerals that are mined as well as their uses.
.....Of the nearly four thousand known minerals, only a few hundred have any current economic value. Of the remaining minerals, no more than a few dozen are abundant. Collectively, these few often occur with each other in the rocks of the Earth's crust and are classified as the rock-forming minerals.