Tourmaline ( TOOR -m? -leen ) is a mineral boron boron silicate coupled with elements such as aluminum, iron, magnesium, sodium, lithium, or potassium. Turmaline is classified as semi-precious stone and gemstones come in various colors.
Video Tourmaline
Etimologi
According to Madras Tamil Lexicon the name is derived from the Sinhala word "thoramalli" (????????) or "t? Rlilili", applied to a group of gemstones found in Sri Lanka. According to the same source, Tamil "tuvara-malli" (??????????) and "toramalli" are also derived from the Sinhalese word. This etymology is also given in other standard dictionaries including the Oxford English Dictionary.
Maps Tourmaline
History
Turmaline brightly colored Sri Lankan jewels were brought to Europe in large quantities by the Dutch East India Company to meet the demand for curiosity and gems. At that time, it was not realized that schorl and tourmaline were the same minerals, because only about 1703 found that some colored gems were not zircon. Tourmaline is sometimes called "Ceyconese [Sri Lanka] Magnet" because it can attract and then dissipate hot ash due to its pyroelectric properties.
Turmalin was used by chemists in the 19th century to polarize the light by shining rays to the surface of gems cut and polished.
Species and varieties
Species and varieties commonly encountered:
Schorl species:
- Blackish brown to black - schorl ,
The Dravite species: from Drave district in Carinthia
- Dark yellow to brownish black - dravite ,
Elbaite species: named from the island of Elba, Italy
- Red or pink-red - granular variations,
- Light blue to bluish green - Brazil indicolite varieties (from indigo),
- Green - verdelite or a Brazilian emerald variation,
- Not Color - achroite variety (from the Greek "???????" meaning "colorless").
Schorl
The most common tourmaline species is schorl , the last part of the sodium (divalent) iron group. This may cause 95% or more of all tourmaline in nature. The earliest history of schorl minerals indicates that the name "schorl" was used before 1400 because a village known today as Zschorlau (in Saxony, Germany) was later named "Schorl" (or a small variant of this name), and the village had a nearby tin mine where, besides kasiterit, black tourmaline was found. The first description of schorl with the name "schÃÆ'¼rl" and its occurrence (various tin mines in the Saxony Ore Mountains) was written by Johannes Mathesius (1504-1565) in 1562 under the title "Sarepta oder Bergpostill". Until about 1600, additional names used in German are "Schurel", "SchÃÆ'¶rle", and "Schurl". Beginning in the 18th century, the name SchÃÆ'¶rl is mainly used in German-speaking areas. In English, the names shorl and shirl were used in the 18th century. In the nineteenth century the names of common schorl schienc schiens schorl and turmaline iron were the words of schorl the English word used for this mineral.
Dravite
Dravite, also called chocolate tourmaline, is a rich magnesium tourmaline endmber endmber. Uvite, in comparison, is a magnesium calcium tourmaline. Dravite forms several series, with other tourmaline members, including schorl and elbaite.
The name dravite was first used by Gustav Tschermak (1836-1927), Professor of Mineralogy and Petrography at the University of Vienna, in his book Lehrbuch der Minerogie (published in 1884) for tourmaline rich in magnesium (and rich in sodium) from the village of Dobrova near Unterdrauburg in the Drava river area, Carinthia, Austro-Hungarian Empire. Today this tourmaline region (type locality for dravite) in Dobrova (near Dravograd), is part of the Slovak Republic. Tschermak gives this tourmaline the name of dravite, for the Drava river region, which is a district along the Drava River (in German: Drau , in Latin: Drave ) in Austria and Slovenia. The chemical composition given by Tschermak in 1884 for dravite is roughly corresponding to the formula NaMg 3 (Al, Mg) 6 B 3 Si 6 O 27 (OH), which is in good agreement (except for OH content) with the weekend dravit formula as it is known today.
The varietas used to describe the amount of carbon dioxide you have in the vanadium.
Elbaite
The lithium-tourmaline Elbait is one of three pegmatitic minerals from Uta, Sweden, where the new alkaline lithium element (Li) was determined in 1818 by Johan August Arfwedson for the first time. The island of Elba, Italy, is one of the first places where colorless and colorless marine biota are extensively chemically analyzed. In 1850 Karl Friedrich August Rammelsberg described fluorine (F) in tourmaline for the first time. In 1870 he proved that all tourmaline varieties contain chemically bonded water. In 1889 Scharitzer proposed a substitution (OH) by F in a red Li-tourmaline from Su 'ice, Czech Republic. In 1914, Vladimir Vernadsky proposed the name "Elbait" for the rich lithium, sodium, and aluminum derivatives of Elba Island, Italy, with a simplified formula (Li, Na) HAl 6 B 2 Si 4 O 21 . Most likely the material types for elbaite are found in Fonte del Prete, San Piero di Campo, Campo nell'Elba, Elba Island, Livorno Province, Tuscany, Italy. In 1933, Winchell published the latest formula for elbaite, H 8 Na 2 Li 3 Al 3 B 6 Al 12 The 12 O 62 , normally used for date is written as Na (Li 1.5 3 O 18 ] (OH) 3 (OH). The determination of the first crystal structure of the Li-rich tourmaline was published in 1972 by Donnay and Barton, performed on pink eagles from San Diego County, California, USA. Chemical composition of tourmaline group
Tourmaline minerals group chemically is one of the most complicated groups of silicate minerals. The composition varies greatly because the substitute isomorph (solid solution), and the formula can generally be written as
- XY 3 Z 6 (T 6 O 18 ) (BO 3 ) 3 V 3 W,
dimana:
- X = Ca, Na, K,? = lowongan
- ,
- Z = Mg, Al, Fe 3 , Cr 3
- T = Si, Al, B
- B = B, lowongan
- V = OH, O
- W = OH, F, O
The revised nomenclature for the tourmaline group was published in 2011.
Physical properties
Crystal Structure
Tourmaline is a six member cyclosilicate ring that has a trigonal crystal system. It occurs during the thick, thick, prismatic crystals and thick columnar usually triangles in the cross section, often with a curved lurik face. The termination force at the end of the crystal is sometimes asymmetric, called hemimorphism. Small slender prismal crystals are common in fine-grained granite called aplite, often forming a radial daisy-like pattern. Tourmaline is distinguished by the prism of its three sides; no other common minerals have three sides. The facial prism often has heavy vertical striations that produce a round triangle effect. Tourmaline is rarely perfectly euhedral. The exception is the fine dravite tourmaline from Yinnietharra, in Western Australia. The deposit was discovered in the 1970s, but it is now over. All hemimorphic crystals are piezoelectric, and often also pyroelectric.
Color
Tourmaline has various colors. Typically, tourmaline is rich in blackish-black iron to dark brown, while the rich varieties of magnesium are brown to yellow, and tourmaline rich in lithium is almost colored: blue, green, red, yellow, pink, etc. Rarely, colorless. Bi-color and colorful crystals are common, reflecting fluid chemical variations during crystallization. The crystal can be green at one end and pink on the other, or green on the outside and pink inside; this type is called watermelon tourmaline. Some forms of tourmaline are dichroic, in which they change color when viewed from different directions.
The pink color of tourmaline from many areas is the result of prolonged natural irradiation. During their growth, these tourmaline crystals incorporate Mn 2 and are initially very pale. Due to natural gamma-ray exposure from radioactive decay 40 K in their granite environment, the gradual formation of Mn 3 ions occurs, which is responsible for deepening the pink to red.
Magnetism
Dark blurred schorl and yellow tsilaisite are idiochromatic tourmaline species that have high magnetic susceptibility due to high concentrations of iron and manganese respectively. Most gem-quality tourmaline is an elbait species. Elbaite tourmalines are allochromatic, degrading most of their color and the magnetic susceptibility of schorl (which imparts iron) and tsilaisite (which implanted manganese).
Turmaline red and pink have the lowest magnetic susceptibility between elbait, while tourmaline with yellow, green and bright blue is the most magnetic elbait. Dravit species such as green chromium dravit and chocolate dravit are diamagnetic. Handheld neodymium magnets can be used to identify or separate some types of tourmaline gems from the others. For example, blue indicolite tourmaline is the only type of blue stone that will show a drag response when a neodymium magnet is applied. Any diamagnetic blue tourmaline can be identified as a copper-colored tourmaline paralba in contrast to the magnetic blue-colored tourmaline stained with iron.
Treatment
Some tourmaline gems, especially pink to red, are altered by heat treatment to enhance their color. Red stones are too dark to be lightened by careful heat treatment. The pink color of pale pink manganese containing manganese can be greatly increased by irradiation with gamma rays or electron beams. Irradiation is almost impossible to detect in tourmaline, and it does not, at present, have an impact on values. Incredibly includes tourmaline, such as rubellite and Brazilian paraiba, sometimes enhanced clarity. Clearer tourmaline (especially various paracids) is much lower than untreated gems.
Geology
Tourmaline is found in pegmatites of granite and granite and in metamorphic rocks such as sekis and marble. Turbochal schorl and rich lithium are usually found in granite and pegmatite granite. Turmaline is rich in magnesium, dravites, generally confined to sekis and marble. Turmaline is a long-lasting mineral and can be found in small amounts as grains in sandstone and conglomerate, and is part of the ZTR index for high-weather sediments.
Locality
Gems and tourmaline specimens were mined primarily in Brazil and Africa. Some placer materials suitable for the use of gems are from Sri Lanka. Apart from Brazil, tourmaline is mined in Tanzania, Nigeria, Kenya, Madagascar, Mozambique, Namibia, Afghanistan, Pakistan, Sri Lanka and Malawi.
United States
Several fine gems and material specimens have been produced in the United States, with the first invention in 1822, in the state of Maine. California became a major tourmaline manufacturer in the early 1900s. Maine sediment tends to produce crystals in raspberry pink and green mint. The California deposit is known for its bright pink, as well as bicolors. During the early 1900s, Maine and California were the world's largest gem turper producers. Queen Mother Cixi of China loves pink tourmaline and buys large amounts of gems and carvings from the new Himalayan Mine, located in San Diego County, California. It is not clear when the first tourmaline was found in California. Native Americans have been using pink and green tourmaline as a funeral gift for centuries. The first documented case was in 1890 when Charles Russel Orcutt found a pink tourmaline in what later became Stewart Mine in Pala, San Diego County.
Brazil
Almost every color of tourmaline can be found in Brazil, especially in the Brazilian states of Minas Gerais and Bahia. In 1989, miners discovered a unique and brightly colored tourmaline in ParaÃÆ'ba state. The new tourmaline type, soon to be known as tourmaline paraiba, comes in blue and green. Brazilian paraiba tourmaline usually contains abundant inclusions. Most tourmalays from Brazil are actually from neighboring Rio Grande do Norte. The materials of Rio Grande do Norte are often less intense in color, but many nice gems are found there. It is determined that the copper element is important in stone staining.
The world's largest
Large tourmalines were cut from Paraiba, measuring 36.44 x 33.75 x 21.85 mm (1.43 x 1.33 x 0.86 in) and weighing 191.87 carats, included in Guinness World Records. A great natural gem, owned by Billionaire Business Enterprises, is bluish green. Perfect oval-shaped cut stones are presented in Montreal, Quebec, Canada on October 14, 2009.
Africa
In the late 1990s, copper-containing tourmaline was found in Nigeria. The ingredients are generally more pale and less saturated than Brazilian ingredients, although generally much lesser materials are included. The more recent African discovery of Mozambique has also produced a copper-colored tourmaline, similar to the Brazilian paraiba. Although the color is slightly less bright than Brazilian material, Mozambique paraiba is often less included and has been found in larger sizes. Mozambique ingredients are usually more colorful than Nigerians. There is significant overlap of color and clarity with the Mozambican paraza and Brazilian paras, especially with material from Rio Grande do Norte. Although cheaper than the high-quality Brazilians, some Mozambique materials are priced at more than $ 5,000 per carat, which is still very high compared to other tourmalines.
Another very valuable variety is tourmaline chrome, a rare type of turboin dravite from Tanzania. Turmaline Chrome is a rich green color due to the presence of chromium atoms in the crystals; Chromium also produces the emerald green color. From standard elbaite colors, the blue indicolite gem is usually the most valuable, followed by verdelite green and rubellite pink to red. There is also a yellow tourmaline, sometimes known as tourmaline canary. Zambia is rich in red and yellow derivatives, which are relatively cheap in the country. The rarest varieties, achroite without color, are not appreciated and are the cheapest of transparent tourmaline.
Afghanistan
Source of the article : Wikipedia
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