Tourmaline stone is found in various colors and its chemical composition is silicate and borate of aluminum, magnesium and iron
Tourmaline is the name given to an important group of gem-quality boron silicate minerals
Tourmaline gemstones can be found in all colors of the rainbow
Due to its variety of colors, it is one of the most widely used stones in today’s world
The name of this stone is derived from the Sri Lankan word turamali, which means a stone with different colors
Tourmaline was first used as a gemstone around 1500, but its many varieties were not identified until 1800
In 1875, George Koons, an American collector, introduced the green tourmaline he found from Mica Mountain mine in Maine, America, to Tiffany & Co., thus attracting a lot of attention to this stone
The main examples of tourmaline include dravite, uveite, schwarel, lidicoatite and alabite
Scoral is the most common variety, accounting for approximately 95% of all tourmaline deposits, but is not considered a gemstone
Most tourmaline stones are from the elbaite family
Because tourmaline consists of a large group of related gemstones, most tourmalines are traded under their color names
Some of the names used include pink-red rubellite, blue-green paraiba, blue indiocolite, and multicolored watermelon tourmaline
There are other names such as colorless acroite, green verdilite and chrome tourmaline
Like sapphire, names like yellow tourmaline or pink tourmaline are used to sell colored tourmalines
:Identification of tourmaline
Tourmaline is a boron silicate that contains amounts of aluminum, iron, magnesium, sodium, lithium, copper and potassium
Tourmaline crystals are three-faceted and can be easily identified
Tourmaline has very distinctive gemological characteristics that help distinguish it
Tourmaline is very hard, has little cleavage and is multicolored
Tourmaline has extraordinary physioelectric properties, which means that its crystals can generate electric charge under mechanical pressure or high temperature fluctuations
This feature has made it known as electric stone
When tourmaline crystals are rubbed, the abrasion creates static energy, and when they are caught on ash or dust
They can attract particles, which is why they are sometimes called Sri Lankan magnets
Tourmaline: sources and origins
Tourmaline is found in alluvial and pegmatite deposits around the world
Tourmaline is the national stone of the United States of America, where it has been mined for centuries
In fact, until the early 1900s, America was considered the primary source of high-quality tourmaline
Today, the most important deposits of tourmaline come from Minas Gerais and Bahia, Brazil
Other important reserves include Afghanistan, Australia, Burma, India, Italy, Madagascar, Malawi, Mozambique, Namibia, Nepal, Nigeria, Pakistan, Russia, Sri Lanka, Switzerland, Tanzania, USA, Zaire, Zambia and Zimbabwe
Tanzania produces high-quality emerald green chrome tourmaline, and in the late 1990s, blue tourmaline containing copper was also discovered in Ningeria, and some time later, another source of this tourmaline was found in Mozambique
Both of these stocks are not as intense in color as Brazilian materials. Zambia produces red rubellite and canary yellow tourmaline, while Afghanistan is famous for producing green verdolite and blue indicolite
:Famous types of tourmaline stones
Acroite: very rare and almost colorless tourmaline
Dravite: Yellow-brown to dark brown magnesium tourmaline
Green colored stones are also known as Chrome Tourmaline or Chrome Dravite
Indicolite: blue tourmaline
Paraiba: copper green, blue, blue-green, light blue tourmaline named after a state in Brazil
Rublite: rich red, reddish pink or purple tourmaline
Scorl: black iron tourmaline
Sybrite: Indigo to purple-blue tourmaline named after finding a source in the Ural Mountains.
Verdelite: green tourmaline
Borgrite: An iron tourmaline named after the American Academy of Sciences
Elbaite: Lithium tourmaline named after the island of Elba
Lidikotite: Calcium tourmaline named after an American gemologist
Tesilasite: A magnesium tourmaline named after a state in Sri Lanka
Watermelon tourmaline: multi-colored tourmaline that shows pink, green and white colors in one crystal
When you cut the crystals, you will see pink in the middle with a white border and green edges
Cat’s eye tourmaline: very rare tourmaline with the effect of light radiation in the shape of a cat’s eye, which is usually green and pink in color
Types of tourmaline stone colors
Tourmaline can be seen in different colors from colorless to black. Colorless tourmaline is the rarest, but also the least valuable
Black tourmaline is the most common color. Most tourmalines have two or more colors in one stone
Tourmaline crystals that show green color on one side and pink to red on the other side and are white in the middle
It is called watermelon tourmaline, tourmaline has strong multicolor, which means that its crystals show different colors according to your viewing angle
Most reds, pinks, browns, and yellows in tourmaline are colored by manganese, while iron and titanium can cause green to bluish-black colors
Lithium impurities make any color like blue, green, red, yellow and pink
Rare emerald green tourmaline is colored with chromium
Many pink tourmaline crystals get their color from the natural process of radiation
Cat’s eye tourmaline is usually green or pink in color
although it has been seen in other colors as well
The most valuable and rare tourmaline is green-blue paraiba colored with copper
Other valuable colors include red-purple rubellite and blue indicolite
When buying tourmaline, color intensity and saturation will be the most important factors
:Transparency of tourmaline stone
Tourmaline usually ranges from clear to translucent
We see its opaque examples in cat’s eye tourmaline
According to GIA, most of the tourmalines are type II materials in terms of transparency, which means tourmaline is usually covered
The degree of roughness also varies according to the type of tourmaline, some colors are more dominant than others
Green tourmaline is usually completely transparent, while pink, blue and red tourmaline such as rubellite, paraiba and watermelon tourmaline are found in many gemstones
Rublite, paraiba and watermelon are in the category of gems with type 3 transparency.Cat’s eye tourmaline usually ranges from semi-transparent to opaque, and this effect is due to needle-shaped inclusions
When we cut and polish the tourmaline, it has a glassy luster and sometimes a bit like a stigma
?How is tourmaline cut
Tourmaline is usually cut into long rectangular shapes because this is how its crystals behave
However, it is found in older forms and a variety of cut styles
Due to the multi-colored tourmaline, tourmalines that are lighter in color are cut from the side perpendicular to the main axis to show the most color
Conversely, darker stones are cut parallel to the main axis
Cat’s eye tourmaline is cut in a wedge shape to show the effect of cat’s eye in the best way
Watermelon tourmaline is cut into watermelon wedges to reveal its attractive colors
?How is tourmaline prepared
Most tourmalines are available without special preparation procedures
However, some of them may be heated to have better color and clarity
Yellow, pink and red tourmaline varieties are placed under the light to make their color more prominent, while the detection of radiation is almost impossible and does not have a great effect on the value of the stone
Rublite and Paraiba may be modified in terms of transparency if their surface is covered
?What are the gemological characteristics of tourmaline
Chemical formula: Na (Li1.5Al1.5) Al6 (Si6018) (Bo3) 3 (OH) 3 (OH) Elbaite: Na (Li1.5, Ali1.5)
Al6Si6O18 (BO3)3 (OH)4
Dravite: NaMg3Al6Si6O18 (BO3) 3 (OH) 4
Lidiquiatite: Ca (Li2Al) Al6Si6O18
(BO3)3(OH)3F
Chrome dravite: NaMg 3Cr6Si6O18
(BO3)3 (OH)4
Crystal structure: triangular, long crystals with triangular cut and rounded edges, distinct grooves parallel to the axis
Color: All colors
Hardness: 7 to 7.5 on the Mohs scale
Refractive index: 1.614 to 1.666
Density: 2.82 to 3.32
Cleavage: unknown
Transparency: transparent to opaque
Bidirectional refraction or birefringence: -0.014 to -0.032
Luster: glassy
Night vision: weak or absent
Gemstones related to or similar to tourmaline
Due to the variety of tourmaline colors, tourmaline crystals should not be confused with famous gemstones such as amethyst, andalusite, yellow beryl, citrine, demantoid garnet, emerald, hydnite, idocrase, kunzite, morganite, peridot, praziolite, ruby, topaz and zircon. they take
Tourmaline is actually a group of minerals and a gemological term used for a variety of related gemstones. Most types of tourmaline are classified according to their color
