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Home » Minerals » Beryl

Beryl


A minor ore of beryllium and one of the most important gem minerals.



What is Beryl?



Beryl is a silicate mineral with a chemical composition of Be3Al2Si6O18. It is found in igneous and metamorphic rocks in many parts of the world. Before 1969 beryl served as the only important ore of beryllium metal. Since then, most of the world's supply of beryllium is refined from bertrandite mined at Spor Mountain, Utah. Small amounts of beryl, produced as a by-product of gemstone mining, are still used to produce beryllium.

The major economic interest in beryl today is its use as a gemstone. The beryl gems are named by their color as emerald (green), aquamarine (greenish blue to blue), morganite (pink to orange), red beryl (red), heliodore (yellow to greenish yellow), maxixe (deep blue), goshenite (colorless). Emerald and aquamarine are the most popular. After diamond, more emerald is imported into the United States by dollar value than any other gemstone. Occasionally chatoyant specimens of beryl are found that can be cut into cabochons to produce interesting cat's eyes.


Geologic Occurrence of Beryl



Beryl is a mineral that contains a significant amount beryllium. Beryllium is a very rare metal and that limits the occurrence of beryl to a few geological situations where beryllium is present in sufficient amounts to form minerals. It mainly occurs in in granite and granite pegmatites; in metamorphic rocks associated with pegmatites; and, in veins and cavities where hydrothermal activity is associated with rocks of granitic composition. These different types of deposits are often found together and serve as an exploration model for finding beryl.

Beryl is also found where carbonaceous shale, limestone, and marble have been acted upon by regional metamorphism. The famous emerald deposits of Colombia and Zambia have been formed under these conditions. The chromium or vanadium needed to color the emerald is thought to be derived from the carbonaceous material.


Physical Properties of Beryl

Chemical Classification silicate
Color green, yellow, blue, red, pink, orange, colorless
Streak colorless (harder than the streak plate)
Luster vitreous
Diaphaneity translucent to transparent
Cleavage imperfect
Mohs Hardness 7.5 to 8
Specific Gravity 2.6 to 2.8
Diagnostic Properties hexagonal crystal form, hardness
Chemical Composition Be3Al2Si6O18
Crystal System hexagonal (occurs in prismatic to tabluar crystals)
Uses gemstones, a minor ore or beryllium


Caesium bearing Beryl
Cesium-bearing beryl from Madagascar. Specimen is approximately 1 inch (2.5 centimeters) across.



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Aquamarine Beryl
A spectacular crystal of aquamarine from the Shigar Valley of Northern Pakistan. This specimen clearly shows the hexagonal form with terminations and a vivid blue color. The specimen is approximately 15 x 11 x 7.5 centimeters in size. Specimen and photo by Arkenstone / www.iRocks.com.




emerald beryl
Vivid green beryl crystals from the Cosquez Mine in Colombia. The cluster measures 5 x 4.2 x 3 centimeters. Specimen and photo by Arkenstone / www.iRocks.com.


red beryl
A specimen of red beryl on matrix from the Wah Wah Mountains of Utah. The specimen measures 4.7 x 3.8 x 3.1 centimeters. Specimen and photo by Arkenstone / www.iRocks.com.


morganite beryl
An interesting specimen of morganite with tourmaline crystals from the Pederneira Mine in Minas Gerais, Brazil. This specimen has been nicknamed the "Sword in the Stone". Approximately 13.8 x 8.0 x 11.7 centimeters in size. Specimen and photo by Arkenstone / www.iRocks.com.


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