other names: Emerald
mineral class: Silicates and germanates
chemical formula: Be3al2(SiO3)6
Chemical elements: Beryllium, aluminum, silicon, oxygen
Similar minerals: Diopside, Grossular, Tourmaline
shine: Glass gloss
crystal structure: hexagonal
mass density: approx. 2.7
magnetism: not magnetic
Mohs hardness: 8
stroke color: White
transparency: transparent to translucent
General information about the emerald:
Of the emerald describes a variety of beryl and is unmistakable because of its bright green color, which can occur in different tones. The characteristic green color of the actually colorless beryl is due to the contained in the emerald ions of the two elements chromium and vanadium, with vanadium colored stones may actually not be called emeralds. Like all other beryl varieties, the transparent emerald has a shell-like breakage and a glassy luster and, with a maximum Mohs hardness of 8, is one of the hard minerals.
Its name derives from the Latin word "smaragdus" and from the ancient Greek word "smáragos", which in turn derive from ancient words of Sanskrit and Hebrew and translated translate as "shine" or "flashing" mean.
Origin, occurrence and localities:
Like all other beryls, emeralds also form in metamorphic rocks, in river sediments and in pegmatite veins. In the relatively small crystals mostly inclusions can be seen, so that eye-clean stones are extremely rare. Therefore, such impurities in the jewelry industry are largely tolerated and the images of emeralds with inclusions as so-called "jardins", so called "gardens". On the basis of the inclusion picture, the location of the respective stone can be easily traced. Significantly rarer are Smaradge with cat's eye effect, which is called in the jewelry production "Chatoyance".
The most important sites for emeralds of exceptional quality are located in Colombia on several smaller mines, which are located mainly in the areas around Muzo and Chivor. There are also some important international deposits in Brazil. Colombian emeralds usually show the jagged three-phase inclusion pattern typical of this region, resulting from liquids, vapor bubbles and salts. Also typical of the mines in Muzo and Chivor are inclusions formed by the smallest paristitic, apaitic or pyrite crystals. If the emerald has acicular or hairy inclusions that look like small bamboo sticks, it is most likely from one of the deposits in the Urals. Important deposits are also found in India, Pakistan and Afghanistan, where stones of exceptionally pure quality are extracted.
History and usage:
The emerald was already in ancient times as a coveted gemstone and was imported from the fourth millennium BC mainly from Egypt, where the captured stones were comparatively small and full of inclusions. Even in ancient Egypt emeralds as well as aquamarines were considered coveted status symbols. Above all, Cleopatra is said to have had a particular weakness for the green gemstones. The most beautiful and purest specimens did not reach Europe until the 16th century, when Spanish explorers discovered some mines in Colombia and Brazil. These stones in Europe achieved higher prices than diamonds. Today, Colombia alone exports emeralds worth up to four hundred million US dollars per year, although this information does not include the black market.