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www.mineralgallery.co.za Minerals A-E |
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Beryl |
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Name
Beryl
Chemistry
Be3Al2(SiO3)6, Beryllium Aluminum Silicate
Uses
As a specimen and for extracting beryllium, also as a gemstone
Color
Emerald green, blue to blue-green, yellow, greenish-gold, red, colorless and pink.
Hardness
7.5-8
Specific gravity
2.6-2.9
Crystals
It crystallizes in the hexagonal crystal system and forms prismatic crystals with striations parallel to their length
Accompanied by:
Phenakite, rutile, quartz, lepidolite and chrysoberyl
Fracture
Conchoidal to uneven
Luster
Vitreous
Cleavage
Basal, poor
Streak
White
Similar to:
Quartz except for the termination.
Beryl, emerald is the green variety and aquamarine is the blue variety.Other colors of beryl are also used as gemstones but are not as well known.
· The greenish-yellow variety is called Heliodor.
· The pink variety is called Morganite.
· The colorless variety is called Goshenite.
The name beryl is used for the red and golden varieties, which are simply called red beryl and golden beryl, respectively. Beryl is colorless in pure form; it is the many different impurities that give beryl its varied coloration. It usually forms hexagonal prism with pinacoid terminations. The terminations are often modified by many different pyramidal faces. Faces on large crystals are often pitted, striated lengthwise and rough.
Beryl, an aluminosilicate mineral, is the principal ore of the rare element beryllium. Long prized as various gemstones, notably the deep- green emerald, the pale blue-green aquamarine, the pink morganite, and the golden heliodor, beryl is easily distinguished by its long, six-sided prismatic crystals (hexagonal system) but also forms compact to coarsely granular masses. The common material is whitish to green and is subtranslucent; gem material is transparent.
Most beryl is found in pegmatite dikes, where large crystals are intergrown with quartz and feldspar, but the emerald variety also occurs in altered limestone and in various metamorphic rocks. Crystal size ranges from tiny to enormous. A crystal weighing 200 tons was mined in Minas Gerais, Brazil, and crystals about 6 m (20 ft) long and 2 m (7 ft) across have been found in the Black Hills of South Dakota and in Albany, Maine. Common beryl has been mined for beryllium since 1925, notably in Brazil, where the largest deposits occur.
