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Chemical Formula | Mg3Al2Si3O12 |
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Composition | Magnesium aluminum silicate. The magnesium is virtually always replaced by some iron, and sometimes with manganese |
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Variable Formula | (Mg,Fe,Mn)3Al2Si3O12 |
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Color | Deep red to nearly black; rose-red to violet |
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Streak | Colorless |
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Hardness | 6½ - 7½ |
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Crystal Forms and Aggregates |
(Isometric) Occurs as single dodecahedrons and trapezohedrons, occasionally well-formed. Also
occurs in dense crystal aggregates and grainy. Crystal faces are usually rounded. Crystals are always embedded unless found in placer deposits, where they are single and rounded. |
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Transparency | Transparent to translucent in thin sections |
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Specific Gravity | 3.5 - 3.6 |
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Luster | Vitreous |
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Cleavage | None |
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Fracture | Conchoidal to uneven |
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Tenacity | Brittle |
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Other Names |  Cape Ruby, Arizona
Ruby, Colorado Ruby, Elie
Ruby |
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Varieties |  Rhodolite -
Rose-red to violet variety of Pyrope. May also refer to
the intermediate member between Pyrope and Almandine [i.e. (Mg,Fe)3Al2Si3O12],
but more commonly used to describe the variety of Pyrope. |
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In Group | Silicates ; Nesosilicates ; Garnet group |
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All About | Pyrope is a Garnet, belonging to
the Garnet group. The Garnet group is a small group
of closely related minerals. The members of the Garnet
group are isomorphous, and some of them freely
intermingle. They vary only slightly in physical
properties, and some of them may be so similar that they
are indistinguishable from one another without x-ray
analysis. The most common members are: Pyrope, Almandine, Spessartine, Grossular, Andradite, and Uvarovite. The minerals in the Garnet group are called "Garnets". All Garnets are hard and many are fit for gem use. Unless articulate, most mineral and gem dealers don't refer to garnets by their true name (i.e. Pyrope), but by the name "Garnet". The garnets as a group occur in all colors (except for blue). For more information about garnets, see the Garnet group. Pyrope is the most popular Garnet. It forms rounded, transparent crystals, which, together with with its deep red color, present a most desirable gem. Pyrope is found along with Diamonds in Kimberlite pipes, and also occurs as rounded, waterworn pebbles in placer deposits. |
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Uses | Pyrope is a popular gem. Its deep
red color gives it special distinction, and it is the
most popular of gem garnets. It is also crushed for use
as an abrasive for the production of Garnet paper. See the gemstone section on garnet |
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Striking Features | Color, crystal form, hardness, and localities |
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Popularity (1-4) | 2 |
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Prevalence (1-3) | 2 |
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Demand (1-3) | 1 |
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Distinguishing Similar Minerals |
Almandine - usually more brownish in color;
usually found in different environments Grossular - not as deep red as Pyrope Andradite - usually occurs in crystal groupings, whereas Pyrope occurs in individual crystals; otherwise indistinguishable by ordinary means Spinel - Occurs in different crystals than Pyrope Ruby - Harder (9), usually lighter in color |
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Commonly Occurs With |
Olivine, Phlogopite, Hypersthene, Arsenopyrite, Magnetite, Diamond |
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Noteworthy Localities |
Pyrope is not a common mineral, and
there are much fewer localities for this Garnet than
other garnets. It occurs in Bohemia, Czech Republic;
Vetarella, Vico, Lazio, Italy; Gorund, Switzerland; and
Elie Ness, Fifeshire, Scotland ("Elie Ruby").
Pyrope is also found in many of the South African Diamond
mines, such as the famous Kimberly Mine. Small amounts of
Pyrope also come from Sri Lanka and Minas Gerais Brazil. In the U.S., the most significant deposit is near San Carlos (in the San Carlos Indian Reservation), Gila and Graham counties, Arizona. Large amounts occur near Fort Defiance (Buell Park and Garnet Ridge), Apache Co., Arizona, and notable deposits exist in the Four Corners area (where the four states of Colorado, Arizona, Utah, and New Mexico meet). Small amounts have also come from Bisbee, Cochise Co., Arizona; Sloan diatremes, Larimer Co., Colorado; and Cowee Creek, Macon Co., North Carolina. In Canada, Pyrope is found in Joli Township, Quebec. Rhodolite, a mixture of Pyrope and Almandine, comes from Cowee Creek, Macon Co., North Carolina. |
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Picture Icon Links |
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