Pyrope (variety of Garnet)
Current inventory:  0 gems
 

  
Pyrope is named from the Greek word pyropos, meaning fire-like in allusion to the red color.

Discovered in 1803; IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

Mg₃Al₂(SiO₄)₃

Magnesium Aluminum Silicate

Molecular Weight:

403.13 gm

Composition:

Magnesium

18.09 %

Mg

29.99 %

MgO

Aluminum

13.39 %

Al

25.29 %

Al₂O₃

Silicon

20.90 %

Si

44.71 %

SiO₂

Oxygen

47.63 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/A.08-10

Nickel-Strunz 10th Ed. ID:

9.AD.25

9 : SILICATES (Germanates)
A : Nesosilicates
D : Nesosilicates without additional anions; cations in [6] and/or greater coordination

Related to:

Garnet Group. Almandine-Pyrope Series. Knorringite-Pyrope Series. Pyrope-Grossular Series.

Members of Group:

Garnet Group: Almandine, Andradite, Grossular, Pyrope, Spessartine, Uvarovite

Varieties:

Chromian Pyrope, Rhodolite, Titanian Pyrope

Synonyms:

Arizona Ruby, Bohemian Garnet, Böhmischer Granat, Cape Ruby, Colorado Ruby, Elie Ruby, Greenlandite (of Klaproth), Pyrope Garnet, Vogesite

Crystal Data

Crystallography:

Isometric - Hexoctahedral

Crystal Habit:

Subhedral to euhedral crystals, showing the dodecahedron or trapezohedral forms, to 20 cm; also granular, massive.

Twinning:

None

Physical Properties

Cleavage:

None

Fracture:

Conchoidal

Tenacity:

Brittle

Moh's Hardness:

7.0 - 7.5

Density:

3.582 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Purple-red, pinkish red, red-orange, deep red to almost black; colorless to pink in thin section.

Transparency:

Transparent to Translucent

Luster:

Vitreous

Refractive Index:

1.714  Isotropic

Birefringence:

0.000 (Isotropic)

Dispersion:

0.022

Pleochroism:

None

Occurances

Geological Setting:

In ultramafic rocks, as peridotites, kimberlites, eclogites, serpentinites, and in "hornblende"-garnet-plagioclase rocks and anorthosites. Also in amphibole and biotite schists, and as a detrital mineral.

Common Associations:

Ilmenite, Phlogopite, Olivine, Hornblende, Plagioclase, Diamond, Kyanite, Rutile, Chlorite, Titanite, Glaucophane, Omphacite

Common Impurities:

Fe, Mn, Ca

Type Locality:

Czech Republic

Year Discovered:

1803

View mineral photos:

Pyrope Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Pyrope is a member of the Garnet Group of minerals that includes Almandine, Andradite, Grossular, Pyrope, Spessartine and Uvarovite. Pyrope is the only variety of Garnet that is always a shade of red. Pyrope is also the only variety of Garnet whose common source is igneous rather than metamorphic rocks. Pyrope is difficult to distinguish from Almandine but is usually clearer and contains fewer internal flaws. Pyrope and Almandine form a mineral series in which iron in Almandine substitutes for the magnesium in Pyrope. In fact, pure Pyrope is unknown in nature and always contains some Almandine and Spessartine components. Rhodolite is the result of the mixture of Pyrope and Almandine of about two to one (Pyrope to Almandine). Malaya is a mixture of Pyrope and Spessartine. Umbalite from the Umba Valley, Tanzania is also a mixture of Pyrope and Spessartine. Pyrope gems are usually fairly small and larger gems sold as Pyrope are most likely Almandines with a Pyrope component.

Some Pyropes show an interesting color change. Material from one location in Norway is wine red in incandescent light and violet in daylight. Some Pyrope from the Umba Valley in East Africa are Pyrope-Spessartines that are greenish blue in daylight and magenta in tungsten light.

Distribution: Widespread. The following localities have all produced substantial amounts of gem material. Around Merunice (Meronitz), Czech Republic. Immense crystals in the Dora-Maira massif, Parigi, near Martiniana Po, Piedmont, Italy. In Germany, from Zöblitz and Greifendorf, Saxony. From South Africa, especially at the diamond mines around Kimberley, Cape Province. Along the Umba River and in the Pare Mountains, Tanzania. In the USA, at Masons' Mountain, near Cowee Creek, Macon County, North Carolina, and from Buell Park, near Fort Defiance, Apache County, Arizona. In Australia, 20 km from Bingara, New South Wales, and at Proston, Anakie, and Ruby Vale, Queensland. From San Martin and Quines, San Luis, Argentina. At Gravata, Pernambuco, Brazil.

  
Pyrope Garnet gems for sale: