Almandine



Almandine

General
CategoryMineral
Identification
Colorreddish orange to red, slightly purplish red to reddish purple and usually dark in tone
Cleavagenone
Fractureconchoidal [1]
Mohs Scale hardness7 - 7.5
Lustergreasy to vitreous
Polish lustervitreous to subadamantine [1]
Refractive index1.790 (+/- .030) [1]
Optical PropertiesSingle refractive, and often anomalous double refractive [1]
Birefringencenone
Dispersion.024 [1]
Pleochroismnone
Ultraviolet fluorescenceinert
Absorption spectrausually at 504, 520, and 573nm, may also have faint lines at 423, 460, 610 and 680-690nm [1]
Specific gravity4.05 (+.25, -.12) [1]

Almandine, also known incorrectly as almandite, is a species of mineral belonging to the iron with increasingly pyrope-rich composition.

Almandine occurs rather abundantly in the gem-gravels of Sri Lanka, whence it has sometimes been called Ceylon-ruby. When the color inclines to a violet tint, the stone is often called Syrian garnet, a name said to be taken from Syriam, an ancient town of Pegu. Large deposits of fine almandine-garnets were found, some years ago, in the Northern Territory of South Australia, and were at first taken for rubies and thus they were known in trade for some time afterwards as Australian rubies.

  Almandine is widely distributed. Fine rhombic dodecahedra occur in the abrasive agent.

References

  1. ^ a b c d e f g Gemological Institute of America, GIA Gem Reference Guide 1995, ISBN:0-87311-019-6
  • This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.
 
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