Beryl
Beryl is a common mineral from the mineral class of " silicates and Germanates ". It crystallizes in the hexagonal crystal system with the chemical composition Al2Be3 [ Si6O18 ] is therefore a beryllium - aluminum - silicate. Structurally, it belongs to the ring silicates.
Beryl developed primarily large, tabular or prismatic to columnar crystals with glass - to -fat -like luster on the surfaces, which can be up to 18 meters long and 180 tons. But he also occurs in the form of granular or massive aggregates that are easily confused with quartz. In pure form, beryl is colorless and transparent. But it may also appear white and accept by foreign admixtures different colors, the transparency may decrease accordingly by multiple refraction due to polycrystalline training.
Due to its high Mohs hardness 7.5 to 8 and its often well-educated beryl crystals is processed mainly to semi-precious stones, with especially the blue aquamarine, the emerald green and pale yellow to greenish yellow beryl are known.
Etymology and history
The word " beryl " was borrowed from the Latin berillus Beryllus and goes back over Greek βήρυλλος, beryllos and berulo Syrian, Chaldean Birula, veruliya Prakrit, vaidurya in Sanskrit.
The Latin Beryllus was used in antiquity as a generic term for all clear crystals: Thus passes away the word goggles ( " eye glasses " ), because the first lenses were ground from the crystal. The derivation is carried parill to prill and brill. The feminine "e" is created later from the more common plural the glasses, since there are two glasses.
From the Latin berillus also the Italian brillare directs " shining, bright ", French briller from whose participle brilliant at the root of the German words Brilliant ( a ground type, and so polished diamond ) and brilliance ( " light sharpness ") forms. In the English but the French loanword an additional "i" receives, well read in the transcript of the francophone pronunciation, and this brilliant English is a common misspelling of the German word to excel in a misconceived analogy " excel ".
The degradation of the beryl variety emerald can be traced back to the 13th century BC in Egypt. But even in pre-Columbian South America, the gem was traded widely.
Classification
Already in the outdated, but partly still in use 8th edition of the mineral classification by Strunz was beryl for mineral class of " silicates and Germanates " and then to the Department of " ring silicates ( cyclo- silicates) ", where he was named the " beryl " with the system No. Formed VIII/E.12 and the other members Bazzit, cordierite, Indialith, Pezzottaite, Sekaninait and Stoppaniit.
The 9th edition valid since 2001 and of the International Mineralogical Association (IMA ) used the Strunz'schen Mineral classification assigns the beryl also included in the department's "Ring silicates ". However, this is further divided according to the structure of the silicate rings, so that the mineral according to its construction in the subdivision - is to find " [ Si6O18 ] 12 six- Simple rings without insular complex anions ", where it likewise eponymous the " beryl " with System no. Forms 9.CJ.05 and the other members Bazzit, Indialith, Pezzottaite and Stoppaniit.
The mainly common in English-speaking classification of minerals according to Dana assigns the beryl in the class of " silicates and Germanates " and then in the Department of the " ring silicates: Six Rings " field. He is also named as the " beryl " with the system no. 61.01.01 and the other members Bazzit, Indialith, Stoppaniit and Pezzottaite within the subdivision " ring silicates: Six rings with Si6O18 rings; possible (OH ) and find Al- substitution ".
Varieties and modifications
The most popular varieties are the green emerald, aquamarine blue, the yellow beryl (also Heliodor ) and the pink morganite (named after the New York banker John Pierpont Morgan ) and colorless Goshenite.
One also rose, cesium-containing beryl is called Vorobieffit.
The very rare red variety Red beryl is outdated also known as Bixbite. This name belongs, however due to the significant risk of confusion with the mineral bixbyite under the provisions of CIBJO to the unwanted trade name.
Education and Locations
Beryl is either formed in magmatic pegmatite and granite or hydrothermally. Greisen in or quartz transitions Also metamorphic formed beryls have been found, including gneiss. It can also be secondary enriched in the form of placer deposits in river sediments.
Some of the many localities include Minas Gerais and Pici in Brazil, Coscuez and Muzo in Colombia, Antsirabe in Madagascar, Spitzkoppe in Namibia, Iveland in Norway, Habachtal in Austria, Gilgit in Pakistan, Malyshevo and Murzinka in the Urals in the Russian Federation, Adun - Chilo in Siberia, as well as Keystone / South Dakota and Pala / California in the United States
Beryl crystals can be exceptionally large. Thus, in the U.S. state of Maine already six feet long, and was found a half -ton copies. Crystals up to 177 tons were found in Namivo / Alto Ligonha in Mozambique.
Crystal structure
Beryl crystallized hexagonal space group P6/mcc ( Raumgruppen-Nr. 192) with the lattice parameters a = 9.22 Å and c = 9.20 Å and two formula units per unit cell.
Use
The raw material
Beryl is the main source of the light metal beryllium, which is used inter alia, in space technology as a component of special alloys. More than 80 percent of the annual world production comes from the United States. In addition, in the Middle Ages beryls were ground into lenses that were used as glasses and this gave their name.
As a gemstone
Beryls all color varieties are processed with good quality gemstones. The emerald was, however, used as one of the first varieties for these purposes and degraded in larger quantities. The oldest mines can be dated to about 1300 BC.
Clear Gemstones usually receive a facet-cut. When grinding, however, it should be of significant in some beryl varieties pleochroism.
Translucent or opaque stones get a cabochon cut. Larger mineral aggregates are sometimes processed into arts and crafts objects.