The mineral pyrope is a member of the garnet group. Pyrope is the only garnet which always displays red color.

It is a Nesosilicate and is in the cubic crystal system. Fractures are conchoidal. Its hardness is 7 to 7.5 in Moh’s scale of hardness. Its luster can vary from greasy to vitreous.

Its name is derived from the Greek words for fire and eye. It is a widely used gemstone though it is less common than most other garnets. Colorado ruby, Arizona ruby, California ruby, Rocky Mountain ruby, Elie Ruby, Bohemian carbuncle and Cape ruby are some of the misnomers employed to denote pyrope.

The composition of pyrope is Mg3Al2(SiO4)3. Iron and manganese may be substituted in stead of magnesium in the pyrope structure. The resulting garnets are defined according to their pyrope-almandine ratio. Rhodite is a garnet consisting of ~70% pyrope.

The origin of most pyrope is in ultramafic rocks, typically perodotite from the earth’s mantle. Pyrope also occurs in ultrahigh-pressure metamorphic rocks. Pyrope found in association with diamond commonly contains Chromium which imparts a distinctive violet to deep purple color with a greenish tinge. This is often used as a kimberlite indicator mineral in certain difficult areas.