Trilateral crystal system
Crystallization habit: columnar, triangular, hexagonal and triangular single cone, and the aggregate is radial, bundle and rod-shaped.
Cleavage and fracture: no cleavage, shell fracture.
Gloss: glass luster,
Transparency: transparent to opaque
Hardness 7.5
Specific gravity 3.06
Refractive index 1.62- 1.64
Birefringence: 0.0 18~0.040, usually 0.020 tourmaline. The mineralogical name is electric tourmaline. The name tourmaline comes from its own unique thermoelectric characteristics. According to legend, during the18th century, several children in Amsterdam, the Netherlands, played with stones brought back by navigators at the seaside and found them in the sun.
Green tourmaline
There is a strange color. I am even more surprised that these stones have the power to attract or repel light objects, such as dust and grass clippings. Therefore, the Dutch call it a lime stone. Later, the famous Swedish scientist Ringnes discovered that tourmaline has piezoelectricity and pyroelectricity, which is the origin of tourmaline's name. Tourmaline is often used to measure the change of luminous intensity and pressure in science. During World War II, it was the only substance that could judge the pressure of nuclear explosion and was widely used in the optical industry. Tourmaline has been used as a gem for a short time, but because of its beautiful color. Tourmaline is bright, clear and transparent, and has become a common name in the jewelry industry. According to historical records, tourmaline is also the favorite of Empress Dowager Cixi. In the funeral of Empress Dowager Cixi, there was a lotus with tourmaline carved at its foot, which weighed 36.8 yuan (about 5092 grams) and was worth 752,000 silver at that time. The most famous tourmaline in the world is produced in Brazil and the United States, among which the bright blue tourmaline found in Brazil is one of the most popular gems in the world. Tourmaline is deeply loved by people of all ethnic groups because of its homophonic "evil spirits". Tourmaline is a mid-range color gem next to diamond, ruby, sapphire and emerald. The surface of tourmaline crystal
There are as many as 15 kinds of multiple colors, which are colorless, mainly including rose red, pink, scarlet, blue, green, yellow, brown and black, among which transparent blue, fresh rose red and pink plus green are the top grades. Tourmaline is rich in color, changeable and transparent. In addition to transparent tourmaline, there is also a translucent tourmaline cat's eye, which has a cat's eye effect. The biggest feature of tourmaline is its large birefringence. When you look at the edges and corners of the faceted gem pavilion with a magnifying glass of ten times, you can clearly see the double shadow. Secondly, tourmaline has two colors. Except for the pink tourmaline made in the United States, the dichroism of tourmalines in other colors is obvious. Seen from two different directions with the naked eye, the colors of gems are obviously different. Some tourmalines have different colors on the inner and outer skins or the upper and lower ends of the same crystal, such as tourmaline crystal produced in San Diego County, California, USA, with green in the middle and red on the surface. Tourmaline crystals produced in Altay, Xinjiang, China are red in the middle and green in appearance. When these minerals are processed into gems, there are two colors at both ends of the gem. This two-color phenomenon is rare among other gems, except radioactive colored crystals. The glass of tourmaline is bright and dazzling. When tourmaline is heated, it will produce positive and negative charges at both ends of the crystal. Therefore, the surface of tourmaline ring rubs quickly on silk or leather, so that it can absorb small pieces of paper near it after generating charge. In addition to the flaky fracture healing surface in the pink tourmaline made in the United States, inclusions are rarely seen in tourmalines of other colors. Less inclusions and clean interior are also a major feature of tourmaline. The color of green tourmaline ranges from thick green blue to green yellow. Tourmaline is a birefringent gem with a refractive index difference between 0.0 18 and 0.040, usually 0.020. Refractive index1.62 ~1.64; Optical properties are negative uniaxial. The bi-color of tourmaline is usually moderate to strong, which is the same as its body color. Many gem crystals absorb more light in the longitudinal direction than in the transverse direction. The gem crystal is light green when viewed from the side, but it may be dark green when viewed vertically. Sometimes,
It's almost dark
Many green tourmalines are clean to the naked eye, and some have cat's eyes. They often contain irregular, linear, separated or staggered liquid and gas inclusions, and may also have mirror-like inflatable cracks. Long hollow growth tubes or sometimes covered with tiny mineral crystals are also typical inclusions.
Some green tourmalines can be distinguished by their bright colors and typical small sizes. A bright blue-green tourmaline produced in Pale, Brazil and colored with copper, commonly known as "neon green". Compared with ordinary tourmaline, its color is more saturated and lighter. Pale tourmaline with one carat or more in green and blue-green is very rare and is the most valuable green tourmaline in the market. A similar blue-green tourmaline colored by copper impurities is also produced in Nigeria.
It has become more common to use crack filling treatment to improve the clean appearance of tourmaline. Another common treatment method is to fill the growth tube with plastic, especially on gems with cat's eye phenomenon; Dark green tourmaline may be heat-treated to dilute its body color, but the result of this treatment is undetectable.
There are many gem materials with similar colors but lower prices, which can be used as substitutes for Pale tourmaline. One is blue-green apatite, often called "aegirine apatite", and its refractive index is 1.63~ 1.64, which is slightly different from Pale tourmaline, but its refractive index is poor. Beautiful gems have always been considered as women's decorations, but they are not. When it comes to the popularity of gems, it is still more closely related to men! Because in ancient times, gems represented a person's wealth and status, and most of them were embedded in men's hats and clothes, especially the green gem-green tourmaline, which showed the elegance of men. In modern times, especially in colored gems, it has become a precious ornament for women, but it seems that men have lost it. Suitable for gem decoration atmosphere! In fact, men also need makeup. Although simplicity and generosity are men's aesthetic standards, exquisite and elegant gems can make your man stand out! Diamonds and rubies are too eye-catching for men, but sapphires and green tourmalines are the best male gems! Especially the green tourmaline, that kind of quiet cold light, like a man's deep wisdom and strong will, is the best gem to show a man's elegance! Green tourmaline is also very suitable for men from the general energy function, because the brilliance of green tourmaline is said to enhance wealth and wisdom! And wisdom and wealth are the ultimate embodiment of men's charm! In fact, men don't need too much jewelry, but a beautiful green tourmaline jewelry is enough! Think of the calm, gentle and wise, or the green light shining on your fingers when you wave. What a handsome wind! If you love him, please send him a green tourmaline ornament, which will make him more chic and manly.
The color concentration range of green tourmaline is very wide, some are very light green, and some are very deep, which can only be revealed by light. Some green tourmalines show a high-quality and delicate green tone like green leeks, while others show yellow-green, olive-green and brown-green tones. Blue-green and bright green are the best and most popular colors, but they are extremely rare. Green tourmaline has become the best choice for many people who don't want to spend a lot of money on emeralds, and it is quite cost-effective to buy green tourmaline with large particles and high purity if the budget is considerable. Men's acceptance of tourmaline is also very high, and some green tourmaline men's ornaments are gradually accepted by the market. When tourmaline contains vanadium or chromium, this green tourmaline will present a very beautiful emerald, which is specially called chromium tourmaline. Its color is much brighter than ordinary emeralds, and its price is very high, almost close to emerald, but it is still warmly sought after by the market. Tourmaline is bright in color, large in particles, flawless inside, novel in shape and polished. The colors are red, blue and green. When choosing inlaid jewelry, the color should be uniform and gorgeous, with red, blue and green as the best. In necklaces and bracelets, it is best to have rich colors, and each bead can have rich colors. What is more valuable is that there are two or more colors on the same tourmaline, that is, two-color tourmaline or multi-color tourmaline, and the watermelon tourmaline with infrared green inside is also more precious. Tourmaline is brittle and prone to cracks, and contains a large number of inclusions inside. The existence of a large number of cracks and inclusions will affect the transparency, color and fire color of tourmaline, and the tourmaline with very pure interior is also rare and belongs to the top grade. With the development of jewelry industry, tourmaline attracts more and more people's love with its crystal clear quality and colorful colors. What is the difference between tourmaline and other precious stones has also become a concern of consumers. Tourmaline is the most colorful stone among natural stones, and there are many similar stones. For example, ruby, red spinel, spodumene, orange-red topaz and red beryl are similar to red and pink tourmalines; Blue tourmaline-like gems have blue spinels; Gems similar to green tourmaline include diopside containing chromium, emerald and green beryl. The main difference between tourmaline and these gems lies in its unique hot spots. When tourmaline rubs on soft cloth, the heat generated can absorb the paper near at hand, coupled with strong dichroism and obvious ridge ghost, which are not available in other gems. What needs attention here is the difference between tourmaline and synthetic two-color crystal, glass and artificial red tourmaline. The synthesized crystal has the thermoelectric effect of electric Baxter, with brownish green and brownish red at both ends, dark color and gray tone. The boundary between the two colors is very clear, and there will be several straight ribbons in the middle. The birefringence is small, and the low-edge ghost is not as clear as tourmaline. In addition, dichroism is not as clear as tourmaline. Glass has a variety of bright colors, and its appearance is somewhat similar to tourmaline. Only the glass has no electrothermal property, low edge ghost and poor dichroism, and circular bubbles can be seen inside. Color-changing tourmaline is a colorless tourmaline, which will turn red after radioactive irradiation. The changed red tourmaline is uniform in color, and its physical and chemical properties are the same as those of natural red tourmaline. The difference is that red is not fresh, accompanied by gray tones, not as gorgeous as natural red tourmaline.