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Chrysoberyl
Current inventory:  0 gems
 

Chemistry:  BeAl₂O₄  [Beryllium Aluminum Oxide]

Discovered in 1789;   IMA status: Valid (pre-IMA; Grandfathered).
The name Chrysoberyl is from the The name Chrysoberyl is from the Greek word chrysos meaning golden, in allusion to the minerals color, and beryl.

Classification

Mineral Classification:

Oxides

Strunz 8th Ed. ID:

4/B.07-10

4 : Oxides & Hydroxides
B : Oxides with metal : oxygen = 3:4 (spinel type M3O4 and related), Alumina-Spinels
07 : Chrysoberyl - Swedenborgite series

Crystal Data

Crystallography:

Orthorhombic - Dipyramidal

Crystal Habit:

Crystals are tabular or short prismatic, to 22 cm; prominently striated

Twinning:

Common, producing either flattened heart-shaped or pseudohexagonal multiple contact and penetration twins.

Physical Properties

Cleavage:

[110] Distinct (rarely observed), [010] Imperfect, [001] Poor

Fracture:

Irregular, Uneven, Conchoidal

Tenacity:

Brittle

Hardness (Mohs):

8.5

Density:

3.75 (g/cm³)

Luminescence:

Weak red in SW and LW UV

Radioactivity:

Not Radioactive

Optical Properties

Color:

Green shades, emerald-green, greenish white, yellowish green, greenish brown, yellow, blue

Transparency:

Transparent to Translucent; may be opaque and chatoyant with oriented inclusions (cat's eye effect)

Luster:

Vitreous (glassy)

Refractive Index:

1.745 - 1.756  Biaxial (+)

Birefringence:

0.008 - 0.012

Dispersion:

r > v;  0.015 (low)

Pleochroism:

Alexandrite: X = red; Y = yellow-orange; Z = emerald-green

Occurances

Geological Setting:

Characteristic of some granite pegmatites associated with high-grade mica schists or reaction zones in ultramafic rocks; also detrital in placers.

Type Locality:

Takowaja, Russia

Year Discovered:

1789

View mineral photos:

Chrysoberyl Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Chrysoberyl is a beautiful gem and well suited for jewelry use. The combination of high hardness (8.5) and indistinct cleavage make it very durable. Although its dispersion is low, it is a very bright and colorful gem. Cat's eye Chrysoberyl is also available. Other gems such as diopside and apatite may be called cat's eyes, but Chrysoberyl was the original cat's eye gem. It is the finest cat's eye of gems. The silky fibers are so fine that a microscope is needed to see the individual fibers. This creates a very sharp cat's eye effect.

Chrysoberyl is not very well known in the gem world. It is somewhat overshadowed by one of its more famous varieties, Alexandrite. Alexandrite is the best known and most valuable variety of Chrysoberyl. The quality of Alexandrite's color change effect is what accounts for its desirability and value. It can change from shades of green or blue-green in daylight to shades of mauve, violet, purple or even red in incandescent light. Alexandrite is also available as a cat's eye gem.
 

  
Chrysoberyl gems for sale:

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