Tourmaline
Tourmaline is the most dynamic mineral family of all gemstones. From solid black crystals like Schorl, to incredibly clear crystals, tourmaline forms in literally every shade of color one can imagine.
Not only does it form in every possible color shade, but it also often forms in bicolor and tricolor crystals, as well as mosaic crystal patterns that are best displayed after the crystals are cut into cross-section plates.
MYTHS AND HISTORY OF TOURMALINE
Tourmaline has a long legacy in many ancient cultures and, due to its wide variety of color shades, has also been confused with other gemstones in the past: Stunning green tourmalines were mistakenly identified as emerald, pink rubellite tourmalines were thought to be They were rubies, and the list goes on. The name tourmaline comes from the ancient Sinhalese word “tourmali”, which means “stones of mixed colors.”
According to the ancient Egyptians, tourmaline crossed a rainbow on its journey from the sun, taking on all the colors of the rainbow before finding its resting place deep in the earth.
For many centuries, the piezoelectric properties of tourmaline were well recognized. In the 1700s, Dutch sailors were the first traders to bring tourmalines to the shores of Europe from Sri Lanka and called the stone “Aschetrekker”, meaning “ash removers”. The electrical polarization within the tourmaline crystals made them a perfect tool for removing ash from your tobacco pipes when cleaning them.
Tourmaline has been highly prized throughout history, and its most recognized admirer was Tzu Hsi, the empress dowager of the Ch’ing Dynasty, who ruled China from 1860 to 1908. The stone was used as a notch, in pins of watch chains, or on the buttons of jackets of the Imperial Court and important people.
Precisely during his reign, the first expeditions in search of gold took explorers to San Diego County, California, where they discovered pink tourmaline. Most of the pink tourmaline mined at the Stewart Mine was intended for the Empress and those around her; They bought everything the mine produced and exported it to China.
A few decades later, in 1989, Brazilian miners discovered a never-before-seen tourmaline, the Paraíba, with very vivid blue tones. This rare stone owes its color to copper sulfate and a very small amount of gold, and commands extremely high prices.
Gem quality stones were discovered in the early 19th century in the United States in the state of Maine, and on Mount Mica next to the city of Paris. In 1972, the neighboring Newry mine in the same region produced exceptional quality and for a short period became the world’s leading source of high quality tourmalines.
It wasn’t until the late 20th century that tourmaline began to see a huge rise in popularity in the gem world. New discoveries of rubellite, green tourmaline and indicolite specimens in Brazil led to a new obsession with this gem family. Later, significant tourmaline deposits were discovered in Namibia, Madagascar and older localities such as those in Maine and California found greater market demand.
The most important discovery of the eighties was made next to a small town of Sao José de Batalha in the state of Paraiba, with stones of a powerful electric blue.
Today, tourmaline is incredibly popular and the value of quality gemstones continues to increase.
PHYSICAL PROPERTIES OF TOURMALINE
Tourmaline colors have many different causes. Typically, iron-rich tourmalines are black to bluish-black to dark brown, while magnesium-rich varieties are brown to yellow, and lithium-rich tourmalines are almost any color: blue, green, red, yellow, pink, etc. Rarely, it is colorless. Bicolor and multicolor crystals are common, reflecting variations in fluid chemistry during crystallization. The crystals can be green on one end and pink on the other, or green on the outside and pink on the inside; This type is called watermelon tourmaline. Some forms of tourmaline are dichroic, changing color when viewed from different directions.
All colored tourmaline gems show pleochroism, meaning their color changes when viewed from different angles. In some tourmaline gems, this effect is barely noticeable, while in others it is very evident. Gemstone cutters should keep this in mind when cutting a tourmaline, so that the finished gem brings out its best color.
It belongs to the trigonal crystallization system and is classified in the group of silicates with a very complex chemical formula where there can be a number of combinations between different elements, and its chemical composition varies considerably from one species to another.
Tourmaline is found in more colors, tones and shades than any other gem, available from colorless to black, through an incredible variety of colorations; It can show each of the colors of the rainbow, and several colors can be combined in the same crystal. The crystals that have a pink color on the inside and a green exterior are known as watermelon tourmalines.
The most characteristic habit is that of very elongated prismatic crystals, with narrow faces of a hexagonal prism and striated vertically.
The crystals are hemimorphic, that is, they lack a center of symmetry, which implies that the crystalline faces that top or end the prism at its two ends do not have the same crystalline shape. This fact affects the physical properties of tourmalines, giving them a marked piezo and pyroelectricity.
The philosopher Theophrastus wrote more than 2,300 years ago that “lyngurion”, probably a tourmaline, had the property of attracting straw, ash or small pieces of wood. This happened when the glass was heated; pyroelectricity. This produced an electric discharge on one side of the glass and an opposite charge on the other side, which allowed the particles to be attracted. That is why tourmaline was called “asshentrekker” or “ash-strip” by the Dutch in the 18th century.
An electrical discharge can also be produced on some crystals by applying pressure on the crystal in the direction of its main axis. This effect is known as piezoelectricity and is widely applied in pressure measuring equipment. Tourmaline has been widely used in the production of measuring instruments for submarines and other high-tech equipment.
Confusions: Tourmaline has the ability to resemble other gemstones, and this has led to confusion. Many red stones in the 17th century Russian crown jewels are actually tourmalines, even though they were believed to be rubies.
In South America, where most tourmaline gems are mined, they are called “Brazilian emeralds.”
Tourmaline carving:
Tourmalines are usually cut in the shape of elongated rectangles. This is due to the long and narrow shape of the source crystal.
Tourmaline is very pleochroic. The darkest color is always observed when viewing through the optical axis and the challenge for the lapidary is to orient the stone to obtain the most beautiful color possible while avoiding inclusions.
To give the best shine, it is necessary that the stone has good proportions. Tourmaline is a durable stone if thermal shock is avoided.
Main mines:
We found fantastic specimens in Brazil, the USA, Canada, Africa, India, China, Russia, Afghanistan and, anecdotally, in Spain, small crystals have been found in Andalusia.
Tourmaline is found in granite and granite pegmatites and in metamorphic rocks such as schist and marble. Lithium- and schorlo-rich tourmalines are generally found in granite and granite pegmatite. Magnesium-rich tourmalines, dravites, are generally limited to schists and marble.
Classification:
Tourmaline belongs to a complex family of aluminum borosilicates mixed with iron, magnesium or other metals that, depending on the proportions of their components, can be formed as red, pink, yellow, brown, black, green, blue or violet. Its vertically striated prismatic crystals can be long and thin, or thick and columnar, and have a unique triangular cross section. They often vary in coloration within a single specimen, lengthwise or in cross sections, and may be transparent or opaque. [Mella, 110] [Simmons, 406] [Megemont, 182]
Although tourmaline can be found on all continents, fine crystal specimens and gems are still considered rare and can be quite expensive. Its great popularity as a gemstone began in 1876, when mineralogist and jeweler George Kunz sold a Maine green tourmaline to the famous Tiffany and Co. in New York, and its fame spread quickly. More recently it has become a favorite of collectors and metaphysical practitioners for its versatile energy properties. [Simmons, 406]
Variedades:
Solo 4 especies de turmalina son de importancia real para los gemólogos: Turmalina negra, Elbaita, Liddicoatita, Dravita
Categoría Elbaíta
La elbaita es la forma más valiosa de turmalina. La mayoría de las turmalinas multicolores y casi todas las piedras preciosas de turmalina son de la variedad Elbaita. La elbaita es alocromática, lo que significa que muy pequeñas cantidades de impurezas pueden ser las responsables de la coloración de los cristales, y puede ser fuertemente pleocroica. Cada color del arco iris puede estar representado por elbaita. Las inclusiones aciculares microscópicas en algunos cristales de elbaita muestran el efecto ojo de gato en cabujones pulidos.
Dentro de la Elbaita, se encuentran varios tipos de turmalina da diferentes coloraciones; Acroita (Color blanco), Indigolita(Color azul), Rubelita (Color rojo a rosado), Siberita (Color púrpura a rojo) y la Verdelita, de color verde.
El nombre de elbaita hace alusión a la Isla de Elba (Italia), lugar donde fue descrita por primera vez.
Fórmula Química de la elbaíta: Na(Li,Al)3Al6(BO3)3Si6O18(OH)4
La Paraíba, con su vivo color azul, es la más cara de la familia de las turmalinas, le sigue la Rubelita, de color rojo a rosa.
Paraiba: La forma más cara y valiosa de la turmalina es la rara forma azul neón o Paraiba. La turmalina Paraiba se descubrió por primera vez en una gema pegmatita en el estado brasileño de Paraiba en 1989.
Es una turmalina azul a verde rara, que contiene cobre. La turmalina paraíba se puede encontrar en colores sorprendentemente brillantes, pudiendo alcanzar miles de dólares por quilate. Se encuentra en una única área; En Paraíba, Brasil, generalmente en tamaños más bien pequeños.
También se ha hallado turmalina con contenido de cobre en Nigeria y Mozambique, de un brillo similar.
Rubelita: El color varía de rojo medio a profundo, de un tono similar al rubí. Rubelita es una de las turmalinas más raras y valiosas. Muchas gemas en las joyas de la Corona Rusa del siglo XVII que se creían rubíes, son realmente turmalinas rubelita.
Indigolita: De tonos azul brillante a colores verde azulado, turmalina indigolita es otro color raro de turmalina.
En Europa se conoce desde 1703, cuando fue traída por los holandeses de la isla de Ceilán, actual Sri Lanka. En la antigǖedad se le atribuían propiedades mágicas gracias a sus marcadas propiedadaes piezo y piroeléctricas. La indigolita debe su color a los elementos hierro y manganeso.
Cromo: La turmalina cromada es verde, pero es considerada diferente de los verdes normales, ya que se deriva del color verde intenso de los elementos con rastro de cromo. Encontrada al este de África, turmalina cromada es rara y generalmente se encuentra sólo en tamaño pequeño.
Bi Color: Con frecuencia, variaciones, zonas y bandas de color en turmalina son deliberadamente acentuadas con el estilo de corte que muestra bandas y zonas de color en la gema.
Sandía: Turmalinas bi-color que muestran una piel verde y un centro rojo; éstas son cortadas a veces en rodajas.
Canary: Turmalina amarilla brillante de Malawi.
Ojo de Gato – Turmalina tornasolada en una variedad de colores. A menudo se encuentra en un verde cálido e intenso.
Cambio de color – Cambia de verde, a la luz del día, a rojo, a la luz incandescente.
Una variedad rara particularmente atractiva es la Cromo Turmalina, procedente de Tanzania, de un color verde muy atractivo causado por el cromo, que es el mismo agente colorante de la esmeralda.
BLACK TOURMALINE
The most common species of tourmaline is schorl, the final member of the sodium (divalent) iron group. It may account for 95% or more of all tourmaline in nature. Opaque black schorlo and yellow tsilaisite are idiochromatic tourmaline species that have high magnetic susceptibility due to high concentrations of iron and manganese, respectively.
Schorl is exclusively black and, unlike other forms of tourmaline, is never transparent or translucent. They are usually elongated and highly striated prismatic crystals. Also as short, stubby prismatic crystals.
LIDDICOATITE
Liddicoatita was not recognized as a separate species from Tourmaline until 1977. Before that time, it was thought to be Elbaite. The color is usually smoky brown, but also pink, red, green, blue or rarely white.
DRAVITA
Dravita, also called brown tourmaline, is the end member of tourmaline rich in sodium and magnesium. Varieties of dravite include dark green chromium dravite and vanadium dravite.
Chakras and different varieties of tourmaline
- Black tourmaline (plover): Root chakra.
- Blue tourmaline (indicolite): Third Eye or throat chakra if the blue is not so indigo.
- Brown tourmaline (dravite): Solar Plexus Chakra.
- Colorless tourmaline (acronite): Crown Chakra.
- Green tourmaline (verdelite): Heart chakra.
- Watermelon tourmaline (green and pink): Heart chakra.
- Multicolored tourmaline (polychrolite): In any chakra that is needed to energize and move energy.
- Purple tourmaline – violet (siderite): Crown Chakra.
- Red/pink tourmaline (rubellite): Heart chakra.
- Yellow tourmaline (dravite): Solar Plexus Chakra.
Lightning
When viewing tourmaline, reds, oranges and yellows will look best under incandescent light, while greens, blues and violets look best in daylight.
Tourmaline Carat Weight and Price
It is common to find tourmaline in large crystal sizes. Large crystal sizes increase the depth and richness of tourmaline color.
Like other gems, when the carat weight of a tourmaline increases, so does the price per carat. However, large tourmaline crystals are simply more abundant than small gems, such as ruby and sapphire. This means that weight-related price increases in tourmaline are less severe than in ruby and sapphire.
Clarity and Inclusion
Different varieties of tourmaline tend to have different clarity. Thus, while clean large tourmalines in blue and blue-green colors are available, almost all red and pink tourmalines will show inclusions to the naked eye. The most common inclusions in tourmaline are fractures and fractures closed with fluid filling. Needle inclusions are also common
