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Chemical Formula | Be3Al2SiO6 | ||||
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Composition | Beryllium aluminum silicate, sometimes with some sodium, lithium, and cesium | ||||
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Variable Formula | (Be,Na,Li,Ce)3Al2SiO6 | ||||
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Color | Bright to pale green, light to dark blue, blue-green, yellow, pink, purple, red, brown, colorless, white, and gray. Some specimens are a lighter color on one end of the crystal than on the other, and some unusual multicolored blue and white or green and white specimens also exist. | ||||
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Streak | Colorless | ||||
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Hardness | 7½ - 8 | ||||
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Crystal Forms and Aggregates |
(Hexagonal) Beryl is famous for its perfect,
six-sided crystals. Crystals are prismatic hexagons, and usually occur individually. Crystals
may be enormous. Some 30 foot long (about 8 meters),
well-crystallized examples are known to exist. Also occurs in short, stubby crystals, and occasionally in tabular crystals and plates. Crystals are usually not terminated, and their bases are either flat or damaged. Even when terminated, they are rarely fully terminated like a bipyramidal hexagon. Also occurs in columnar aggregates and massive. Only rarely found in drusy or platy aggregates and as bundles of thin, long crystals. Crystals are usually striated lengthwise with very fine striations. |
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Transparency | Transparent to opaque | ||||
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Specific Gravity | 2.6 - 2.9 | ||||
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Luster | Vitreous | ||||
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Cleavage | 3,1 - basal | ||||
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Fracture | Uneven to conchoidal | ||||
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Tenacity | Brittle | ||||
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Other ID Marks | Occasionally fluorescent yellow, light blue, purple, pink, or red | ||||
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Varieties | The varieties of Beryl are given names based
on their color. All the variety names are accepted by
all, except for Bixbite, which is not recognized by most
authorities. Emerald - Green to dark green Aquamarine - Light to dark blue, blue-green Morganite - Pink to light purple Golden Beryl -Golden yellow Heliodor - Yellow, yellow-green, brown Goshenite - Colorless to white Red Beryl - Deep red (only comes from one locality in Utah) Peach Beryl - Orange-pink Green Beryl - Pale green Bixbite - Strawberry red Bazzite, which is categorized as an individual mineral species, is in essence Beryl, but contains scandium replacing some aluminum. Formula = Be3(Al,Sc)2SiO6 |
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In Group | Silicates ; Cyclosilicates | ||||
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All About | Beryl occurs in a great diversity of colors,
and the dark green variety Emerald is one of the most
precious gems. Only deep green Beryl is called Emerald;
light green Beryl is known simply as "Green
Beryl". Certain specimens of "Green Beryl"
can be heat-treated to form deep blue Aquamarine. Beryl is naturally transparent, however inclusions may cause it to be opaque. Some opaque specimens contain inclusions of fibrous minerals, and, occasionally, the fibers are parallel. If polished, such a specimen displays asterism or chatoyancy. Pure Beryl is colorless. However, a wide range of impurities cause the diverse amount of colors. The green in Emeralds are caused by traces of chromium, and the blue in Aquamarines are caused by iron. Huge, opaque, crystallized hunks of Beryl occur, and these are useful for extracting the rare metal beryllium. |
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Uses | Beryl is the main source of the element
beryllium (formerly known as glucinium). Beryllium is a
very tough metal, and is used in alloys to strengthen the
metal. Beryl forms some of the most well-known and prized gems. The deep green variety Emerald is one of the most valuable of gems. Aquamarine, a semi-precious gem, is the most popular light blue gem. Other Beryl varieties are also faceted for the gem market. "Red Beryl" is rarely worn in jewelry; it is faceted only for collectors due to its rarity. Fine shaped Beryl crystals are very popular among mineral collectors. See the gemstone section on beryl See the gemstone section on emerald See the gemstone section on aquamarine |
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Striking Features | Crystal form and hardness | ||||
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Complex Tests | Insoluble in acids | ||||
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Popularity (1-4) | 1 | ||||
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Prevalence (1-3) | 2 | ||||
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Demand (1-3) | 1 | ||||
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Distinguishing Similar Minerals |
Apatite - much softer (5) Quartz - softer (7), crystals striated horizontally (whereas Beryl crystals are striated vertically) Feldspars - softer (6), has good cleavage Topaz - occurs in different crystals. However very hard to distinguish in massive form Tourmaline - occurs in different crystals, crystals more heavily striated |
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Commonly Occurs With |
Quartz, Feldspars, Calcite, Muscovite, Pyrite, Spodumene, Tourmaline, Cassiterite, Apatite, Barite, Dolomite | ||||
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Noteworthy Localities |
There are many excellent Beryl localities;
only a select few are mentioned here: Emeralds: The finest Emeralds come from Muzo and Chivor, Colombia. Fine material has also come from Minas Gerais, Brazil and the Ural Mountains of Russia. Emeralds have also come from the Cobra and Somerset Mines in Transvaal, South Africa, and the Habatchal, Austria. In the U.S., the only significant Emerald deposits are in North Carolina. The most productive and famous locality there is Hiddenite, Alexander Co. Small amounts from North Carolina have also been found in Shelby, Cleveland Co.; Big Crabtree Mountain, Alexander Co.; and Franklin, Alexander Co. Aquamarine: Beautiful, large, clear, and well-crystallized Aquamarines come from numerous places in Brazil, in the states of Minas Gerais, Bahia, and Esperito Santo. Exceptional specimens also come from central Madagascar, where the Aquamarine is associated with Morganite. Two other fine localities include Mungo, Baltistan, Pakistan and the Ural Mountains of Russia. In the U.S., Aquamarine is found along with other Beryl varieties in many of the localities listed below (in "Other Beryls"). Other Beryls: In the U.S., many fine Beryl specimens of all varieties occur in the pegmatites of the New England states. Some important localities are: Topsham, Sagadahoc Co., Maine; Mount Mica, Paris, Oxford Co., Maine; Branchville and Haddam Neck, Connecticut; and the Ruggles Mine, Grafton Co., New Hampshire. Excellent Aquamarine and Goshenite crystals come from Mt. Antero, Chaffe Co., Colorado. Beautiful examples of Morganite, as well as Aquamarine and Goshenite were found in Pala and Mesa Grande, San Diego Co., California. Fat, stubby crystals occur in Dixon, Rio Arriba Co., New Mexico, and gigantic masses in the Black Hills of South Dakota. The Wah Wah Mountains in Millard Co., Utah is the only locality where bright red Beryl ("Red Beryl") has been found. Strawberry red beryl ("Bixbite") occurs in the Thomas Range, Juab Co., Utah. |
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Picture Icon Links |
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Picture Links | 1. Various Beryl crystals | 2. Emerald crystals in matrix |
