Difference between revisions of "Pyrope"

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Malaia garnet (or malaya) is the red-orange variety of pyrope-spessartite.<br />
 
Malaia garnet (or malaya) is the red-orange variety of pyrope-spessartite.<br />
The name is derived from the Swahili word for prostitute (which freely translates to "outcast") [see: Swahili - English Dictionary].
+
The name is derived from the Swahili word for prostitute (which freely translates to "outcast") [see: Swahili - English Dictionary; Rouse, 1986].
  
 
==Localities==
 
==Localities==

Revision as of 06:46, 23 December 2007

Pyrope Garnet
Chemical composition Mg3Al2(SiO4)3

Magnesium aluminum silicate

Crystal system Cubic
Habit Dodecahedra
Cleavage None
Hardness 7.0-7.5
Dispersion Medium, 0.022
Optic nature Isotropic
Refractive index 1.730-1.760
Birefringence None
Specific gravity 3.65-3.80
Lustre Vitreous

Pyrope is a red, orange-red, brownish-red to pink species of the garnet group which forms isomorphous series with almandine, spessartite and grossular. Pyrope, like all other species of the garnet group, is seldom seen having its ideal chemical makeup.


Diagnostics

Spectroscope

Pyrope has a chromium spectrum that can be combined with the typical spectrum of almandine.

Inclusions

  • Rounded crystals of low relief
  • Rutile needles

Polariscope

Pyrope (in all its isomorphous series) may show anomalous birefringence.

Refractometer

The refraction index of pyrope is 1.714 but, because it is never found pure, its index has a lower value of 1.730 and an upper value of 1.760.

Pyrope is singly refractive (isotropic).

Specific gravity

Pure pyrope has a specific gravity of 3.58. Due to isomorphous replacement, this value is never measured. Instead, its value ranges from 3.65 to 3.80.

Pyrope sinks in all common heavy liquids

Varieties

Rhodolite

Faceted Rhodolite Garnet
Photo courtesy of Rick Martin, Art Cut Gems

Rhodolite is the purple variety of pyrope-almandine. The name and color come from the flower of the rhodondendron.
The jewelry trade sometimes describes every purple garnet as a rhodolite but it should be reserved only for those having an intermediate chemical composition between pyrope and almandine.

Malaia

Faceted Malaya Garnet
Photo by Jeff Scovil
Courtesy of R.W. Wise Goldsmiths

Malaia garnet (or malaya) is the red-orange variety of pyrope-spessartite.
The name is derived from the Swahili word for prostitute (which freely translates to "outcast") [see: Swahili - English Dictionary; Rouse, 1986].

Localities

  • South-Africa
  • USA
  • Russia

References