The name of this stone is derived from the Sinhalese “turmali”. The stones which were brought to Amsterdam in 1703 from Ceylon were called tourmalines. But it was known that local jewelers used this name to determine yellow zircons, which were found in the fields of tourmaline as well. Therefore, there is also a suggestion of combining “tura mail”, also having the Sinhalese origin, which meant “the stone of mixed coloгrs”. According to another version “turmali” can mean “attracting ash” – such a “property” (that isб the ability to get electrified) is characteristic of tourmaline as well.
Formation of Tourmaline and Features of the Structure
Tourmaline is formed in pegmatites and granites, hydrothermal and pneumatolytic lodes in metamorphic rocks (crystalline limestone or shale). Quite often the impact of acidic fluid rising from beneath the Earth’s crust on the rocks is the reason for the formation of tourmaline. Tourmaline crystals have a prismatic shape, the prism face is often covered with shading. Another tourmaline characteristic is the phenomenon of dichroism (colour change considering a different angle), which is presented most vividly in the types of greenish or brownish colour. This optical effect is taken into account by jewelers while choosing the right direction of cutting. In particular, if cutting of the stones with a fibrous structure is performed properly, it is possible to observe a “live”, shimmering color. Tourmaline crystals tend to have a glassy luster and are strongly electrified even while rubbing against the fabric.
It is known that the colouring of tourmaline is very diverse: not a single gemstone is represented in so many colours and shades. Tourmaline crystals are rarely uniform in color: as a rule, different parts of the stone are of different colours, shades can often be contrasting and colour transitions are sharp enough. Tourmaline colouring is traditionally dependent on impurities that the mineral includes: for example, the inclusion of manganese gives pink and reddish shades, chromium and iron – green and blue.
Depending on the type of colouring, there are many types of tourmaline. For example, rubellites are the stones of red, all shades of pink or crimson colour. This variety of tourmaline is valuable, especially – the stones with deep thick cherry-red or ruby-red hues. Achroites, transparent crystals of tourmaline (may also be of very pale shades of green) are very rarely found. Green stones are called verdelites: tourmalines of emerald green colour are of the greatest value (they are also called “Brazilian emeralds”). Chrome tourmalines are the stones of brighter, more intense shades of emerald. Chameleinites are the type of tourmaline, which has a marked “alexandrite effect”: in daylight olive-green colour appears, and in artificial light brownish-red shades occur. Canary Tourmalines are yellow stones. The shade can be bright, or there may be slight colour impurities. The name “canary” means “canary yellow” colour. Note that large crystals of this type are very rare. White tourmalines are valued only for their rarity.
Polychrome tourmalines are extremely astonishing stones, as the colour of the stones can be a miniature composition of all because of a change in one component of the mineral. So “the head of Moor” type (or “the head of blackmoor”, “black head”) appeared: the stones are colorless or pale green and have black “tips”. “Turk’s head” tourmaline is also colorless or has pale-green shades, but the tip is red. The most famous and interesting variety of polychrome stones is called “watermelon tourmaline”: the middle of the stone (or the core) is red, the outer side (or the edge) is green, and the intermediate layer between the edge and the middle is white. Externally, these stones really resemble a slice of watermelon, besides, of very natural colours. Tourmaline of rainbow colour (layers of different colours “fall” on each other) are called “papazheos”. Tourmaline variety of black colour is called schorl.
Indicolite is a blue tourmaline. Such stones are also conventionally called the Brazilian, Eastern or Viennese sapphires, aquamarine tourmaline. This stone was brought to Europe from the island of Ceylon in the 18th century. The most rare type of indicolite is the stones of blue colour. In general, the characteristic colour of indicolite is the shades of greenish-blue or dark blue. There are also stones with neon-blue chatoyancy. Indicolite also possesses dichroism, zonal distribution of colour can be observed. To intensify the colour, indicolites are treated by heat – so intense emerald-blue shades are exerted. Colour modulations are a characteristic feature of inticolite: for example, in different directions the hue and colour density can vary from pale blue to bright blue, turquoise chatoyancy can occur as well. The stones of very dark, “ink” colours, which after heat treatment show a mysterious indigo colour, are found rather often.
It is a very old, very rare and very beautiful stone, which is difficult to compare with the best jewels, because it has a unique beauty and, it is rather one of the rarest gems of the world, each of which can be called a little “wonder of the world” …
The story of discovery of this stone is very confusing. But there is some speculation that the first Paraiba tourmaline was discovered in 1987 by Heitor Diaz Barbos in the village of Sao Jose de Batalha (Brazil, State of Paraiba). It is known that he dreamt that his village became famous for the discovery of a strange stone, and so he spent all the time in tunnels and mines. Let’s just say that this finding surpassed his expectations. According to another version, Paraiba tourmaline was found in the development of pegmatites 500 years ago. Considering the fact that the name of the stone was given in honor of the area where it was found – it turns out that both versions have a common place of stone discovery, which is very important.
Paraiba tourmaline conquered the leading jewelery houses of the world: this stone was often the highlight of “Cartier” and “Tiffany” collections. The main distinguishing feature of this kind of tourmaline is the colour with the “neon” play of colour. One can often hear saying that these stones seems to be “electrified by the play of light”. This feature owes to the specific composition: the structure of the stone contains chromium and vanadium – the sources of bright and “fresh” green hue, and copper and magnesium give a unique blue or dark blue colour. If the structure includes manganese, pink shade that discolours the stone appeares.
But such crystals are heated at the temperature of + 500 ° C, after that they become neon blue. Paraiba tourmaline colour is most clearly revealed after cutting the stones, besides, blue-turquoise shades and fantasy neon blue colour play appear even in low light conditions. The main deposits of these unique stones remain in Brazil, but they are also found in Nigeria, Madagascar and Mozambique. The most valuable ones are still Brazilian tourmaline.
Usage of Tourmaline
This stone is highly appreciated by jewelers all over the world. Due to the fact that tourmaline is soft enough, it is almost not used in producing rings and other items, in which the stone is subject to strong mechanical wear or damage. Polychrome tourmalines are valued by collectors, because each of these stones is unique. Tourmaline can be used as inlays in exclusive interior decoration, or mosaics of natural stone.
Deposits of Tourmaline
The most significant deposits of tourmaline are in California and Brazil. Indicolites are mined in the United States, Sweden, Namibia, Brazil, Madagascar and Sri Lanka. Gorgeous stones of dark blue colour are produced in Afghanistan. Tourmalines of brownish and yellowish-green colour are produced on Ceylon, deposits of verdelite are found in Thailand. “Head of Moor” type of tourmaline was found on the island of Elba. Colourless tourmaline achroite was first found in Switzerland. It is noteworthy that the largest crystals were discovered in Brazil: the total weight of the huge splice of crystals was about 4 tons.