The main component of olivine is silicate of iron or magnesium, and it also contains elements such as manganese, nickel and cobalt. The crystals are short or thick columns. Olivine metamorphism can form serpentine or magnesite, which can be used as refractories. Olivine is an intermediate variety of forsterite (Mg2Sio4) and fayalite (Fe2Sio4) series. The name refers to olive green, which is common in all kinds of magnesium. Olivine is named for its olive green. Its English name is olivine or olivine, the former comes directly from French olivine, and the latter is a mineralogical term. Olivine was discovered about 3500 years ago on St. John's Island, an ancient Egyptian territory. Gem-grade olivine is divided into strong yellow-green olivine, golden-green olivine, yellow-green olivine, strong green olivine (also known as dusk emerald or western emerald, evening primrose emerald) and sapphire (produced in meteorites, very rare). High-quality olivine is transparent olive green or olivine yellow-green, and its clear and beautiful color is very pleasing to the eye, symbolizing peace, happiness and tranquility. In the wars between some ancient tribes, olivine was often given to each other to show peace. Some temples in Jerusalem are still inlaid with olivine thousands of years ago. Olivine is a silicate mineral with island structure, and its chemical molecular formula is (Mg, Fe)2[Sio4], which belongs to orthorhombic system. The crystal morphology is often short columnar, and the aggregates are mostly irregular granules. The colors are mostly olive green, yellow green, golden green or emerald. This kind of glass is shiny and transparent. The refractive index is 1.654- 1.690, and the birefringence is 0.035-0.038. Polychromaticity is not obvious, and dispersion is 0.020. The hardness is 6.5-7.0, and the density is 3.27-3.48g/cm3. Fragile, poor toughness, easy to crack. The general chemical formula of the composition is R2Sio4, and the crystal belongs to nesosilicate mineral family and has an orthorhombic (orthogonal) crystal system. Often olive green, hence the name olivine. In the chemical formula, R is mainly a divalent cation of magnesium, iron and manganese. Because of isomorphic substitution between them, magnesium silica-fayalite, iron silica-manganese silica (fayalite-manganese olivine) and manganese silica-magnesium silica (manganese olivine-magnesium olivine) series can be formed. Members of forsterite-fayalite series are very common. The intermediate member of this series (Mg, Fe)2[Sio4], commonly known as olivine, is the most common in nature. The crystals are short columns and often form granular aggregates. Magnesium-rich color is light, usually yellow tone, while iron-rich color is dark, with glass luster and fracture grease luster. The hardness of moss is 6-7, and the specific gravity increases with the increase of iron content, which is 3.3-4.4. Olivine is the main mineral that constitutes the upper mantle, and it is also the main mineral component of meteorites and moonstone. As the main rock-forming mineral, it is commonly found in basic and ultrabasic magma. Forsterite is also produced in magnesium skarn. Olivine becomes serpentine under the action of heated liquid. Transparent, bright and flawless olivine crystals can be used as gems. The ancient Egyptians in BC decorated with olivine. The ancient church in Cologne, Germany, is inlaid with high-quality olivine gems. Chemical composition olivine is mainly composed of two end-member components, Mg2Sio4 and Fe2Sio4, which are completely isomorphic mixed crystals. Iron-rich members sometimes have a small amount of Ca2+ and Mn2+ instead of Fe2+, while magnesium-rich members can have a small amount of Cr3+ and Ni2+ instead of Mg2+ in addition to Fe3+ and Zn2+. Genetic occurrence olivine is one of the main components of mantle rocks. All kinds of basic and ultrabasic rocks in the earth's crust that are ejected or invaded by mantle materials contain a lot of olivine. In the process of contact metamorphism and regional metamorphism, magnesium carbonate rocks will become olivine due to metamorphism. Metamorphic iron-bearing sediments and dolomite limestone are completely composed of olivine. Olivine is also one of the main minerals that constitute stony meteorites. Olivine contains no time, so it cannot be produced in granite. Mineral characteristics Olivine is a kind of nesosilicate mineral with the chemical molecular formula of (Mg, Fe) 2 [SiO2], which is usually composed of forsterite) Mg2Sio4 and fayalite Fe)2[Sio4]. It belongs to orthorhombic system. The crystal morphology is often short columnar, and the aggregates are mostly irregular granules. Pure forsterite is colorless to yellow; Pure iron olivine is green and yellow; It turns brown or brown after oxidation. Most of them are olive green, yellow green, golden green or emerald. Grease luster, transparent. The refractive index is 1.654- 1.690 and the birefringence is 0.035-0.038. Therefore, under the magnifying glass, there will be a ghost surface at the bottom of the cut olivine. Polychromaticity is not obvious, the dispersion is 0 olivine.020, hardness is 6.5-7.0, and specific gravity is 3.27-3.48. Conchoidal fracture has poor toughness and is easy to crack. The mineral most similar to olivine is neohalite, which is a brownish-yellow or greenish-brown mineral with orthorhombic crystal system, and its composition is Mgaibo4. Its specific gravity is 3.47 ~ 3.49, and its low, medium and high refractive indexes are 1.668, 1.699 and 1.707 respectively. The world-famous British Museum once mistook a boehmite for olivine. This gem is produced in Sri Lanka and Myanmar. Mineral occurrence olivine is a very common rock-forming mineral and one of the earliest minerals formed in the process of magma crystallization. Common in gabbro, basalt, peridotite and other dark basic or ultrabasic rocks, becoming accessory minerals or main minerals. * * * Biogenic minerals are anorthite and pyroxene. The world's largest gem-grade olivine is produced on Zabajad Island in the Red Sea, weighing 3 19 carats. It is now in the Smithsonian Institution Museum in Washington, USA. The olivine found in Damaping, Wanquan County, Zhangjiakou, Hebei Province, China, weighing 236.5 carats, was named "Star of North China" and is the largest olivine in China. In addition, there is a square emerald-cut dark green olivine of 146 carats in geological museum, London, which comes from Zebelgert. Basic attribute 1. Crystal system and crystal habit oblique crystal system: the crystals are mostly short columnar or coarse. An ordinary simplex has two parallel faces. Refractive index test of olivine: rhombic column and rhombic bipyramid. Gem-grade olivine is mostly irregular columnar, but it is rare to be intact. 2. Multicolor, mainly yellow-green, with a small amount of brownish green or brown. Polychromaticity is weak. 3. Gloss and transparency: glass luster, transparent to translucent. 4. Optical properties: biaxial crystal, positive or negative optical properties change with composition. 5. Refractive index and birefringence: RI: 1.65- 1.69, RI: 0.036, the brown variety is slightly higher. 6. Dispersion: 0.020, medium. 7. Absorption spectrum: The three absorption bands in the blue region are 453 nm, 473 nm and 493 nm respectively. 8. Hardness: 6.5-7, which varies with the composition. 9. Relative density: 3.32-3.37, which varies with different components. The typical spectrum of olivine is 10. Cleavage fracture: poor cleavage, shell-like fracture 1 1, crystal inclusion, water lily leaf inclusion, negative crystal, gas-liquid inclusion and cloud-like inclusion in olivine. [Edit this paragraph] World-famous high-quality olivine producing areas include St. John's Island in the Red Sea, Mount Vesuvius in Italy, Nallam in Norway, Eiffel in Germany, Arizona and New Mexico in the United States. Gem-grade olivine is found in zircon halo-waxy-basanite xenoliths in the eclogite from Zhangjiakou, China. Uses and efficacy gems (olivine is a green and clear gem). Olivine is often used to make brooches, rings and earrings. It is a common mid-range gem in the jewelry market. Olivine is ground into powder, which can be used as medicine to treat asthma and put under the tongue to relieve thirst caused by high fever. Olivine helps to relieve tension, make people relaxed and happy, and also make people sleep well, which is more harmonious with the lotus leaf content in olivine. Green energy helps to accumulate wealth. It can be used as a talisman to ward off evil spirits and help to improve liver disease. [Edit this paragraph] Gems similar to olivine identification points include green tourmaline, zircon, diopside, ludwigite, emerald, calcium-aluminum garnet and so on. The key basis for the distinction is: a. the difference between refractive index and birefringence; B. absorption spectrum; C. relative density; D. the inhomogeneity and characteristics of the multi-faceted edge double shadow line; E. differences in gloss, tone and multicolor. Foliaceous inclusions of olivine and water lily: typical yellow-green color is the distinguishing feature. The crystal is inclined columnar, with dense longitudinal lines on the surface, and in most cases it is broken or pebble-shaped. Green tourmaline: the aggregate or crystal fragments of triangular prism, hexagonal prism and triangular single cone, with dense longitudinal stripes on the crystal surface and spherical triangle in cross section. Zircon: tetragonal column, tetragonal bipyramid and its polygon, with sub-rhombic luster and weak multicolor. SG is big. I feel heavy. Diopside: monoclinic gemstone with short columnar and broken crystals, low hardness, poor wear resistance and obvious multicolor. Bauxite: brown to yellowish brown, with obvious polychromatic color. Emerald: Triple crystals are pseudo-hexagonal, plate-like and thick-plate-like, broken into pebbles, and the crystal surface has bright glass luster. Eclogite: The complete crystal forms are rhombic dodecahedron and quadrangular octahedron, and growth line can be seen on the crystal surface. Quality evaluation Olivine is widely distributed in the world, with more output. Olivine used for jewelry should be completely transparent, and its contents should be too small to be seen by the naked eye. Dark green is the best color, with uniform color and a gentle velvet feeling. The purer the green, the better. The more yellow, the lower the price. Olivine earrings with large olivine particles are rare (of course, they are more common than high-grade gems such as diamonds, rubies, sapphires and emeralds). Generally under 3 carats, olivine with 3- 10 carat is rare, so the price is better. Olivine exceeding 10 carat is rare. The world's largest olivine comes from Sebout, Egypt, weighing 3 10 carat, and the most beautiful piece of cut olivine weighs 192.75 carat. It once belonged to the Russian czar and now only exists in. Buying olivine in August is the birthday girl, and many friends know about olivine because they were born in August. The unit price of olivine in green gemstones is not very high, generally around 300-500 yuan/carat. Generally, olivine sold in the market does not exceed 10 carat. Most of them are from Myanmar or Chinese mainland. Among the olivines I have seen, the olivine in Myanmar is slightly green with yellow, not as green as the olivine produced in Makouping, Hebei Province, China. Because the unit price of olivine is not high, it is best to choose a larger one in the purchase, and the color is emerald green. Olivine is often used as brooches, rings and earrings, and attention should be paid to avoid collision with other gems and damage. The key to purchasing (1) When purchasing olivine jewelry, we should first pay attention to whether its green color is pure and deep, and too much yellow-green color will reduce its value. (2) Note that there can be no cracks inside, and defective olivine has low value. (3) Pay attention to whether there are burrs in the gem. It is best to choose the one with straight edges and perfect cutting rules. Note: There are many fake olivine inlaid ornaments, please pay attention to distinguish them! The material of olivine, the main stone used in this kind of jewelry, is very few, so it is difficult for the naked eye to distinguish between true and false. The best way is to directly ask for formal gem identification! Maintaining olivine is fragile. If heated suddenly, it will break and have poor toughness. If the packaging is not good, the collision will be damaged in transit. When processing jewelry, be careful not to work under a blowtorch. Besides, olivine is also afraid of acid corrosion. Pay attention to the gentle operation when replacing stones. An experienced worker, when processing olivine jewelry, always carefully takes the stone out of the tire with green tourmaline, and then processes it. Olivine should not be washed in acidic solution. Some chemicals in the solution will destroy its surface. If heated again, the whole stone will be destroyed. The best way to clean olivine is to use a brush and gently scrub it with soapy water in clean water. It is not a good idea to clean olivine with steam, and olivine is not suitable for ultrasonic cleaning machine. Olivine is easy to be scratched, so loose stones should be wrapped in paper bags alone. If they are put together, problems will inevitably occur when they collide with each other. Cultural Appreciation In ancient times, olivine was called "the jewel of the sun". It was believed that olivine was as powerful as the sun and could exorcise evil spirits. The color of olivine is gorgeous and pleasing to the eye, which is deeply loved by people and gives people a relaxed and happy feeling, so it is known as the "stone of happiness". Many countries in the world have listed olivine and silk-wrapped agate as "birthstones in August", symbolizing gentleness, intelligence, family happiness and harmony between husband and wife.