Zircon, also known as zircon, is the birthstone of December, symbolizing success. (Birthday stone in December, turquoise and lapis lazuli) Its English name is zircon. Zircon is a mineral name, which used to be called zircon and hyacinthus orientalis, and transparent zircon gem.
Chemical composition of zircon: zirconium silicate; The chemical composition is Zr[SiO4], and the crystal belongs to the island structure silicate mineral of tetragonal system. Crystals are short columns, usually square columns, square bipyramids or complex square bipyramids. Zircon has a variety of colors, such as colorless, purple, tan, light yellow, reddish, green, and generally colorless, blue, red and other varieties. High dispersibility and diamond luster. No cleavage. Mohs hardness is 7.5-8 and specific gravity is 4.4-4.8.
Theoretical composition (WB%): zirconia 67. 1, silica 32.9. Sometimes it contains mixed substances, such as MnO, CaO, MgO, Fe2O3, Al2O3, TR2O3, ThO2, U3O8, TiO2, P2O5, Nb2O5, Ta2O5 and H2O. The contents of impurities such as H2O, TR2O3, U3O8, (Nb, Ta) O5, P2O5 and HfO2 are relatively high, but when the contents of ZrO2 and SiO2 are relatively low, their physical properties also change, their hardness and relative density decrease, and they often become amorphous. Therefore, many varieties are formed: Shankoushi, TR2O3 10.93%, P2O517.7%; Dashanshi, TR2O3 5.3%, P2O5 7.6%; Miaomushi, TR2O3 9. 12%, (Nb, Ta)2O5 7.69%, with high uranium and thorium content; Cyrtolite with high contents of TR2O3 and U3O8 is named after the crystal plane bending. Hydrated zircon containing H2O2 ~10%; Beryllium zircon, BeO 14.37%, HFO 26.0%; Hafnium-rich zircon, HfO2 can reach 24.0%.
Zircon is an accessory mineral in various igneous rocks. Alkaline rocks and alkaline pegmatites are rich in comprehensive minerals, which are famous in southern Norway and Urals region of Russia. Zircon is also often enriched in placer. The world's important gem-grade zircon is produced in Laos, Cambodia, Myanmar, Thailand and other places. There are also gem-grade zircon in alkaline basalt in eastern China. Zircon is the most important mineral raw material for extracting zirconium and hafnium, and it is also used in national defense and aerospace industry.
Zircon is a silicate mineral, which can be divided into two types according to its physical properties and chemical composition: high type and low type. Most of the crystals with complete crystallization are "high type"; Those with poor or no crystals are "low type". There are also three types: high, medium and low. But in terms of gem value, high-type zircon is more valuable.
Zircon is a kind of natural gem with high dispersion value and refractive index second only to diamond. Colorless and transparent zircon resembles diamond and is a good substitute for diamond. Commonly used zircon is colorless, reddish brown, reddish brown, green and so on. However, the most popular colors are blue and colorless, among which blue is of high value and generally undergoes artificial heat treatment. Many zircon on the market are sold after heat treatment. This is because the treated gemstone is more beautiful and more marketable than the original gemstone.
Zircon crystal belongs to tetragonal system, a0=0.662nm, c0 = 0.602nm；; Z=4. In this structure, Zr and Si are alternately arranged along the C axis to form a tetragonal body-centered unit cell. The crystal structure can be regarded as a combination of [SiO _ 4] tetrahedron and [ZrO _ 8] triangular dodecahedron. [ZrO8] triangular dodecahedron is closely connected in the direction of B axis in the form of * * * ribs.
Complex tetragonal biconical crystal, D4h-4/mmm(L44L25PC). The crystal is square, biconical, columnar and plate-shaped, and its shape is closely related to its composition. Principal simplex: quadrangular column M, A, quadrangular bipyramid P, U, complex quadrangular bipyramid X. Knee twins can be formed. You can connect with xenotime in a conventional way.
Color: light yellow, bordeaux, light red, blue, green, smoky gray, etc. Glass to diamond luster, fracture grease luster. Transparent to translucent. The hardness is 7.5~8. The relative density is 4.4~4.8. Because it is often radioactive, it causes its own amorphization, and its transparency, luster, density and hardness all decrease.
X-rays emit yellow light, cathode rays emit faint yellow light and ultraviolet rays emit bright orange light.
Under polarizer: colorless to light yellow, with strong dispersion and large refractive index. No= 1.9 1~ 1.96，Ne= 1.957~2.04。 The refractive index of isotropic body decreases, N= 1.60~ 1.83.
The melting point is 2340~2550℃. Under the oxidation condition, it is stable at1300 ~1500℃; It decomposes at 1550~ 1750℃ to produce zirconia silica. Linear thermal expansion coefficient 5.0? 8? 710-6/℃ (200 ~1000℃), and it has good thermal shock resistance and stability. It does not react with CaO, SiO2 _ 2, C and Al _ 2O _ 3 at high temperature, and has strong slag corrosion resistance and does not stick to steel.
Widely distributed in acidic and alkaline magmatic rocks, often occurring in basic rocks and intermediate rocks.
[Identification features] Square short column, square double cone. High hardness and diamond luster. The difference between rutile and rutile lies in its high hardness, and rutile has perfect cleavage. Unlike cassiterite, zircon has a smaller density. Different from monazite, zircon has a square columnar crystal shape and high hardness.
[Industrial Application] The main mineral raw materials of zirconium and hafnium are extracted. The main industrial uses of zircon are as follows: refractories; Molding sand material; Ceramic raw materials; Gemstone raw materials.
Zircon contains radioactive uranium (U) and thorium (Th). But the content is very low, far below the safety factor. So you can wear zircon jewelry with confidence.
Zircon is a kind of gem with special properties. High refractive index, strong dispersion, colorless or light blue varieties have diamond-like strong fire after processing. Because of its similar appearance to diamonds, it is known as a gem comparable to diamonds.
As early as in ancient Greece, this beautiful gem has been loved by people. According to legend, among the twelve kinds of precious stones worn by Jewish bishops, zircon is called "Xia Xinsi". It is said that the nickname "Hyacinth Stone" of zircon originated from "Xiaxinzi" and is now popular in Japan, Hong Kong, Chinese mainland and other places.
Zircon originated from the Arabic meaning of Zhu and the meaning of gold. In ancient India, zircon was called "eclipse stone". This also shows that the color of this gem is common in red, golden yellow and colorless. On the other hand, zircon was very popular in ancient Arabia, Persia and India.
As we all know, many things can be denatured after heat treatment, and so can zircon. If the low-type zircon is heated to a certain degree, it will become a colorless and transparent crystal. For example, zircon in Sri Lanka is mostly green and low-type. After heat treatment, the color becomes obviously lighter and becomes a high-type zircon gem. Red and brown zircon produced in Hainan Province, China, can become colorless after heat treatment.
Zircon, turquoise and lapis lazuli are listed as December birthstones in the gem world, which symbolize victory and good luck and are the guarantee of success.
Some red or brownish red zircon in China can be directly ground into beautiful gems without discoloration treatment. However, it should be noted that China's red low zircon is also a kind of gem with strong dichroism. If red zircon is red when viewed from one direction, it is pale or almost colorless when viewed from another direction. Therefore, when processing, it must be ground in a certain direction, so that the front of the ground mold will appear red.
The famous producing areas of zircon are Sri Lanka, Thailand, Laos and Cambodia. Zircon produced in Yunnan, China generally needs heating to change color.