Emerald

Introduction

Deep green coloured crystal in a rock with brown, sparkling matrix

Uncut emerald. R26566. Source: Geoscience Australia

Emerald is 1 of the precious stone varieties of the mineral beryl. They are highly valued stones used for jewellery. Gems mostly get their color considering of certain trace metals or impurities contained in the mineral, and in the case of emeralds, they incorporate traces of chromium, or sometimes vanadium, giving them an intense green colour. Gems of lighter light-green colour (and sometimes fifty-fifty yellowish colour) are referred to as green beryl.

Other varieties of beryl include:

  • goshenite (colourless),
  • aquamarine (bluish-green colour),
  • heliodor (the rarer yellow variety), and
  • morganite (even rarer peach-pink variety).

Properties

Two translucent, green crystals with brown smudges

Green beryl from Torrington, NSW. Source: Geoscience Australia

Emeralds are fabricated from beryllium aluminium silicate. Although emeralds are hard, they tin can interruption relatively easily due to imperfections in the crystals such as trapped h2o, gas, small fractures or inclusions of other minerals. Still, dissimilar many other gemstones, these impurities, do not detract from the value of a stone. Some crystals from Torrington in New South Wales prove color zoning. These gems are mostly clear beryl with bands of emerald in them. Oftentimes these gems are cutting to heighten the banding effect.

Crystals of beryl can reach a not bad size. According to the Guinness Book of Records, the largest emerald (in matrix) was found in Madagascar. It is 1.25 thou long and weighs 536 kg. Many of the largest crystals have come from the eastern Andes in Colombia and Bahia in Brazil.

The Backdrop of Emerald
Chemical Symbol Be3Al2Si6O18
Name The proper noun emerald is from the Ancient Greek word "smaragdos" meaning dark-green stone and was originally for a variety of green coloured minerals.
Relative density ii.6-2.ix m/cm3
Hardness vii.5 on Mohs Calibration

Uses

Jewel-quality beryl and emerald is used in the jewelry trade.

Beryl can too be used to as a source of glucinium, a high-strength, lightweight metal with a loftier resistance to corrosion. Beryllium has a wide variety of applications, including the industry of electric equipment, nuclear reactors, electronic components and aerospace components. The beryllium extracted from beryl crystals at the Triple Chance mine, Cleaved Hill were used by NASA for the Apollo Space Programme.

History

Emeralds have been prized for thousands of years and feature in myths and legends from many cultures. There is show that emeralds were sold in Babylonian markets over 4000 years ago. In Greek mythology, Hermes gave a behemothic emerald as a souvenir for Aphrodite and in the Hebrew tradition an emerald was one of the four precious stones given to Solomon.

One of the most famous collections of gems, including emeralds, was endemic by the Ancient Egyptian queen, Cleopatra, over 2000 years ago. Cleopatra endemic the emerald mines of Egypt which were taken over past the Romans afterward her death. The Romans continued to mine for emeralds until the sixth century AD.

The Egyptians likewise believed the gems could cure eye diseases and that the green color of emeralds represented fertility and rebirth. For that reason, emeralds were placed at the throat of a mummy for protection during the journey into the underworld and to ensure the deceased person would have strength when they were reborn in the afterlife. In India, emeralds were revered then much that they were inscribed with sacred text and worn as talismans by the aristocracy, including Shah Jahan, architect of the Taj Mahal.

Emeralds from Colombian mines were existence used by people from Mexico, Peru and Chile by nearly thou AD. In the mid-1500s, the Spanish forcefully took over several of the larger mines in Colombia, including the largest producing mine, Muzo, from local tribes. They enslaved and killed many of the locals in the procedure. By the mid-1600s the Spanish had brought South American emeralds to Europe and across Asia. In 1985, divers recovered 2000 Colombian emeralds from a Spanish galleon that had sunk in 1622.

Muzo mine in Colombia is still known for having a murderous reputation. Criminal offense related to emeralds from the mine, was prevalent during the 1970s and 1980s.The esmeraldos, or emerald bandits, who live in the hillsides effectually the mine, were often involved.

The 341 kg Bahia Emerald has also been the centre of international controversy. Information technology was discovered in Brazil in 2001 and is comprised of 9 crystals ranging in size from 22 cm to 3.7 cm long. It was moved to USA and eventually seized by Los Angeles detectives in 2008 afterward a gem dealer reported information technology stolen. The emerald is now locked away due to ongoing disputes over ownership. There were nine men, 1 woman and iii corporations that claimed to own the emerald. In add-on, the government of Brazil claimed that the stone was mined illegally and should be returned. The Bahia Emerald has been the subject of many books, a graphic novel and National Geographic documentary.

In Commonwealth of australia, emerald and green beryl was first mined nigh Emmaville in New S Wales in 1890. Even so, only a pocket-sized proportion of the beryl extracted was of adept quality so the mine closed in 1897. Pocket-size mining and prospecting continued from 1908 to 1963 with niggling success. The Triple Take a chance mine near Broken Hill operated from 1960 until 1990 and was known for its large yellow beryl crystals, some over a metre in length, although not of jewel quality.

In Western Australia emeralds were discovered near Poona in 1912 in metamorphic rocks (mica schist) and pegmatite. Small-scale mining operations and prospecting has been occurring intermittently at Poona since so, including the evolution of the Agha Khan Mine in the 1940s. Underground mining began at the Agha Khan Mine in 1979, but ceased in 1980 due to mining problems and a lack of quality gems. The Menzies deposit was discovered in 1974 and irregular mining has taken place since and so.

Formation

OGreen emerald crystals extruding out of a grey and white coloured rock.

Emeralds from Pilbara, Western Australia. Source: Geoscience Commonwealth of australia

In Australia, emerald is associated with granite pegmatites and metamorphosed rocks called schists. It is too sometimes associated with contradistinct limestones or can be found embedded in calcite or quartz. A pegmatite forms when a magma cools, leaving some elements behind in the remaining fluid. Emerald crystals may grow when the remaining solution cools as long equally the necessary elements are present, including beryllium. Emeralds can also form in veins in the crust from hot liquids that escape from a deeper magma.

Synthetic emeralds are referred to every bit 'created emeralds' and accept been produced by flux-growth or hydrothermal processes. In the flux-growth process, crystals are created by dissolving chromium, beryllium and other elements in a molten flux and allowing crystallisation to occur on a seed of beryl. The flux is comprised of chemicals that stay liquid at high temperatures, such as lithium oxide, molybdenum oxide and vanadium oxide.

The hydrothermal synthesis technique involves dissolving components in an acidic solution at high temperatures and pressures, with crystallisation occurring in a cooler chamber. A method has also been developed for producing an emerald overgrowth on colourless beryl.

Resources

The mineral beryl occurs throughout Commonwealth of australia. However, generally the crystals are non gem-quality and then nearly mining is conducted to extract beryl every bit a source of glucinium. The New England area of New Southward Wales has produced most of the gem-quality beryl, emerald and aquamarine. The largest eolith is constitute in the Emmaville surface area, just there are deposits most Inverell, Dundee and Glen Innes. In the early on 1900s over 53,000 carats (x kg) of beryl and emerald were produced over 20 years in this area. An effort at commercial mining took place at Torrington in the early on 1990's but didn't continue because of the low quantities of gems produced.

Nearly all product of emerald in Western Australia has been from a deposit at Poona simply there are beryl and emerald deposits at Menzies and in the Pilbara region, south of Port Hedland. Mountain Isa in Queensland has beryl-bearing metamorphic rocks and, pocket-sized volumes of aquamarine have been found near Mount Surprise in Queensland and Olary in S Australia.

Well-nigh industrial beryl production from New Southward Wales has been from pegmatites in the Broken Loma area, but beryl has as well been extracted from gravels near Blackness Range, Albury, Ophir, Cooma, Bungonia, Kiandra and associated with alluvial tin deposits at Stanborough, Tingha and Copes Creek.

See map.

Mining

Emeralds accept been commercially mined in Australia in three master deposits Poona and Menzies in Western Australia, and Emmaville in New South Wales. The emeralds are commonly in rocks among layers of other minerals such equally mica. Open up pit mining or terrace mining are the well-nigh common methods. Miners dig a pit with shovels, excavators or other earth moving equipment, depending on the scale of the mine. If the emerald-bearing ore is beneath a substantial embrace of soil and rock, explosives might be used to remove this material. Sometimes high pressure h2o is used to blast the rock to reveal mineral bearing rocks. Tunnels are also used to excerpt emeralds from deeper stone layers.

Emeralds are removed from the exposed zone using hand chisels. In some larger mines security staff transport whatsoever emeralds recovered from the mine to processing facilities in a locked box.

Processing

Screens are used to sort the emeralds by size and and then silt and clays are washed abroad to expose the emerald-bearing schist. No other chemicals are used in this process. Any schist or other rock still fastened to the emerald is removed manually in a process called cobbing. Higher quality materials can be cleaned using high-pressure air.

Emeralds usually contain many cracks, fissures, and inclusions — for this reason, nigh emeralds are immersed in oil to reduce the visibility of the inclusions and improve clarity. Emeralds can exist cutting into many shapes, or even carved, but, because they are brittle, they are often cut into a rectangular shape. The 'emerald cut' is designed to minimise breakages of the crystal in corners, while emphasising the colour of the gem.