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Garnet is the name given to a group of chemically and physically similar silica minerals. The history of garnet dates back to the Bronze Age, more than 5000 years ago. Its name, which has been used since these ancient times, was derived from the Latin word granatium, which means pomegranate (because the small, red crystals were thought to resemble pomegranate seeds). The original name was actually granat, but in time the name morphed into the name garnet.
Garnet is relatively common in highly metamorphosed rocks and in some igneous rocks. Because this group of minerals forms under high temperatures and pressures, the surrounding rock is left with an imprint of this great stress. Because of this, garnet may be used by geologists to gauge how much temperature and pressure the surrounding rocks endured.
Garnets are isostructural, meaning they all share the same crystal structure. This leads to similar crystal shapes and properties. Garnets generally produce symmetrical, cube-based crystals. The most common crystal shape among this group is the rhombic dodecahedron, a twelve-sided crystal with diamond shaped (rhombic) faces. The basic shape is a trademark for garnets, for no other crystal shape is so closely associated with a single mineral group.
Different varieties of garnet contain different metal ions, such as iron, aluminum, magnesium, chromium, or calcium in their structure.
Garnet can be found worldwide. Some notable producers of garnet include: