Tanzanite - a blue stone from Africa

The first tanzanite was discovered in July 1967 by Manuel de Souza, an Indian-born prospector of expensive stones. That is, he is credited with the discovery, because in fact the blue crystals were found in northeastern Tanzania by Masai herders, for whom they had no value. The Masai showed Manuel de Soza the location of the crystals, who was able to appreciate the value of the find. Initially, he thought the mineral discovered was dumortierite or sapphire. However, research by the Gemological Institute of America showed that the stone from Africa was a previously unknown mineral.

Initially christened the new gemstone as "blue zoisite," but soon the American jeweler, vice president of the Tiffany Company, recognized the potential of this very rare stone and decided that such a name did not appeal to women. He gave it the name "tanzanite" - after its place of origin. The godfather of tanzanite Henry Platt revealed in a later interview that the blue gemstone was planned to be called "tiffanyite" or "plattite," but the name "tanzanite" turned out to be more apt. According to him, tanzanite is the most beautiful blue gemstone that has been discovered in 2,000 years.

Finds of tanzanite have also been reported in the Hindu Kush region of Pakistan, but the stones there neither match African stones in purity nor quality of color.

Properties of tanzanite

Tanzanite is a mineral of the silicate group with the chemical formula _Ca2Al3(_SiO4_)3OHand is at the same time a blue variety of zoysite. Crystals of tanzanite are prismatic and often show surface striations. Large crystals of this mineral are rare and on average range from 0.5 to 10 carats (1 carat = 0.2 g).

The luster of tanzanite is described as glassy, on fresh breakthrough surfaces also pearly. The mineral is transparent to translucent. Exemplars of tanzanite that look very clean, and in which no inclusions can be seen with the naked eye, are encountered much more often than those that are completely free of blemishes even under tenfold magnification. Tanzanite has excellent flakiness and an uneven fracture.

Tanzanite shows a hardness of 6.5 to 7 on the ten-point scale of Mohs, a German mineralogist. In this respect, it is comparable to quartz and belongs to the hard minerals. Although it does not meet the hardness criterion for gemstones, which must be above 7 on the Mohs scale, due to the rarity of tanzanite, this blue stone is nevertheless defined as precious. The density is 3.2 to 3.4 ^g/cm3.

Tanzanite color

Tanzanite has a blue color in various shades: light blue, gray-blue, ultramarine, indigo, royal, sapphire, violet-blue and blue-violet. For this reason, tanzanite has been confused with other blue gemstones and minerals like amethyst, azurite, spinel, blue diamonds, sapphire and cordierite.

In recent decades, it has been discovered that larger crystals have a particularly intense, strong color. Most mined tanzanites are pale blue or grayish blue. The most sought-after and most expensive are blue-violet tanzanites, that is, such stones in which the tone of blue predominates over purple. Having both blue and violet color, which is especially evident in cut tanzanites, is called pleochroism in mineralogy (the phenomenon of color change depending on the polarization of light passing through the object).

The reason for the blue color of tanzanite is the trace amounts of vanadium found in it. For this reason, the blue mineral has been included in the group of allochromatic minerals - those whose color is due to external, rather than structural factors.

Completely natural, in any way untreated tanzanite is rather rare. Only a few specimens correspond to the intense blue-violet ideal. The stones are usually either too bright, irregularly discolored, or marked with yellow or brown spots.

The most common method of improving and correcting the color of tanzanite is annealing. Raw stones are heated to a temperature of 370-390°C. The process lasts a maximum of half an hour, when the intensity of the blue color increases. This is explained by the oxidation of vanadium ions. In any for annealing only undamaged tanzanites are suitable. Stones with cracks or gas-filled gaps would break during the procedure.

It is also possible to change the color of zoisite completely yellow or brown to tanzanite, as long as it contains vanadium. During annealing, there are changes in the degree of oxidation of vanadium, which manifests itself as a change in color to blue. It is not always possible to find out whether tanzanite has undergone color correction treatment, as the seller is not obliged to make such a declaration. What is different, however, is coating, i.e. applying a layer containing cobalt to tanzanite, which increases the blue luster of the stone.

Applications of tanzanite in jewelry making

Tanzanite is a mineral of hydrothermal origin, crystallized from hot liquids in veins and fissures. It is still mined in the same place where the first specimens were found. The only known location in the world so far for this rare mineral is in the Merelani Hills region of Tanzania. Since the mineral's resources here are limited, one has to expect a further increase in the price of tanzanite in the future. Probably no other gemstone shows such an upward price development.

Tanzanite is of importance primarily in the form of valuable jewelry. Since its discovery in the 1960s, this blue stone has fascinated with its color and has become a popular gemstone and advanced to the most expensive minerals in the world. The price of tanzanite is significantly influenced by its rarity. A large supply of tanzanite is unrealistic, known deposits are on the wane and striking crystals of high quality (purity, color) will become increasingly rare. According to estimates, tanzanite stocks will last for some 20 years, which means that tanzanite can already be considered a good capital investment.

Tanzanite, used for making jewelry, is offered in a variety of cuts. When choosing a cut, the purity of the stone plays a major role. Cloudy, opaque tanzanite crystals will receive a rather smooth cabochon cut.

Crystal clear and radiant blue tanzanites will be given a facet cut, which will highlight the purple and blue in the play of light involving pleochroism. The most common tanzanite cut is the round oval cut, but also octagonal, teardrop, baguette, cushion, marquise and other cuts.

Compositions with tanzanite are just as varied as the cuts, ranging from purist designs with a single stone to richly decorated jewelry backed by additional sparkling stones, such as zircon, white sapphire or white diamonds. In contrast, jewelry with raw tanzanite stones is based on uncut crystals mounted in earrings, rings or necklaces.

Tanzanite and zodiac signs

Astrologers have so far not yet identified any zodiac sign that is particularly associated with tanzanite. Some of them believe that the mineral patronizes the element of Fire, which means Aries, Sagittarius and Leo. Hot and energetic Fire signs need peace of mind, which a tanzanite amulet can give. The stone will impart wisdom to them and teach them to make the right decisions.

Others believe that the favorites of the stone are the Air signs - Twins, Libra and Aquarius. But on them the mineral has a completely different effect, helping to determine important choices. Creative and versatile Air signs often can't find their way, which hinders their success.

Tanzanite has an interesting significance in the lives of Water signs. Fish, Cancer and Scorpio are very sensitive to any disputes around them. Tanzanite will provide these signs with peace of mind and free them from mental anguish, which will certainly lead to positive changes in their lives.

Those born under Earth signs are real workaholics who, in the fervor of their activities, can forget absolutely everything. It would seem that with such a morbid love of work, you can't even hope to save your family. However, Tanzanite helps strengthen the family ties of Taurus, Virgo and Capricorn, and does not allow you to forget about your duties.

About one thing all experts agree: absolutely all zodiac signs can wear tanzanite and it will not harm anyone.

The largest tanzanite in the world

The largest tanzanite ever found is called "The Mawenzi." It was discovered in 2005 and weighs 16839 carats (3.367 kg). Another tanzanite stone named "Kilimanjaro" weighed about 11,000 carats in its raw state.