How to identify jadeite

Fluorite, also known as fluorite, is a mineral. Its main component is calcium fluoride (CaF2), which contains many impurities. Ca is often replaced by rare earth elements such as Y and Ce. In addition, it also contains a small amount of Fe2O3, SiO2 and trace amounts of Cl, O3, He, etc. Fluorite in nature often shows bright colors, and its hardness is lower than that of a knife. It can be used to prepare hydrogen fluoride:
CaF_ 2+H_ 2SO_ 4=CaSO_ 4+2HF\uparrow
Basic properties of fluorite
Crystalline system and crystallization habit
Fluorite is of equiaxed crystal system. The single crystal is mainly cubic, and a few are rhombic dodecahedron and octahedron. Grid-like stripes parallel to the edges often appear on the crystal surface of the cube, and the aggregate is granular, crystal cluster, strip, block, etc.
optical properties 
*Color: Pure fluorite is colorless, but it contains more Y, Ce, Ca and other elements, resulting in the vacancy of fluorite structure and the color of color center. Common colors include light green to dark green, blue, green blue, yellow, wine yellow, purple, violet, gray, brown, rose red, dark red, etc.
*Gloss and transparency: glass luster; Transparent to translucent.
*Optical property: homogeneous.
*Refractive index: 1.438 (± 0.01)
*Polychromism: No polychromism.
*Luminescence: fluorite can have purple or purplish red fluorescence under ultraviolet light, and fluorite can emit purple or purplish red light under cathode ray; Some fluorites have thermoluminescence, that is, they can emit phosphorescence when heated on an alcohol lamp or exposed to sunlight. In addition, purple fluorite has the characteristic of triboluminescence.
*Spectral absorption: The absorption spectrum of visible light of fluorite is not characteristic, and changes greatly. Once there is absorption. The absorption line is obvious.
mechanical property 
*Cleavage: the four sets of {111} cleavage of fluorite are complete.
*Hardness: Hm=4.
*Density: 3.18 (+0.07, - 0.18) g/cm3.
Varieties of fluorite
The jewelry industry often divides the varieties of fluorite according to its technological use and color characteristics;
By process purpose
According to process use, fluorite can be divided into gem grade and jade grade.
*Gem grade: single crystal is large in size, transparent and bright in color. Because of its low hardness, it is rarely used for jewelry, but mostly for viewing and collecting.
*Jade grade: It is a granular or fibrous aggregate, translucent, with single color or different colors alternating in a strip distribution. It is mostly used for carving or making craft ornaments.
By common colors
Fluorite can be divided into green, purple and blue varieties.
*Green fluorite: blue-green, green, light green. The more common is crystal cluster. The ancient saying of soft water and green crystal is not used now.
*Purple fluorite: deep purple, purple, often distributed in strips. It was called soft water amethyst in ancient times, but it is not used now.
*Blue fluorite: gray-blue, green-blue, light blue, often with deep surface and shallow center.
*Yellow fluorite: orange to yellow, often appearing in strips.
*Colorless fluorite; Colorless transparent to semi-transparent appear as single crystals or clusters.
Optimization and identification of fluorite
*Heating treatment: heating treatment is common in fluorite. Dark blue to black fluorite can be turned into blue by heating. Generally speaking, this kind of heated fluorite is difficult to identify, and its color is stable in the environment below 300 ℃.
*Filling plastic or resin: filling plastic or resin in fluorite, the main purpose of which is to heal surface cracks, so that no cracks will occur during processing or wearing. The identification of fluorite after filling treatment mainly includes the following aspects:
1. Zoom in and check the gap.
2. Test fusible resin and plastic with hot needle.
3. UV fluorescence observation shows that the filled plastic and resin can have characteristic fluorescence.
*Irradiation treatment: colorless fluorite can produce purple by irradiation. The fluorite treated by irradiation is extremely unstable and will fade when exposed to light, so this treatment method has no practical value.
Quality evaluation of fluorite
Gem-grade fluorite shall be transparent, free of mottling and bright in color. The jade-grade fluorite aggregate is required to be fine, dense and large in size.
Brief introduction to the origin of fluorite
The world's gem fluorite is mainly distributed in the United States, Colombia, Canada, the United Kingdom, Namibia, Austria, Switzerland, Italy, Germany, the Czech Republic and Slovakia, the former Soviet Union, Australia, South Africa and other places. For example, Illinois and Kentucky in the United States produce purple, violet, blue, yellow, brown and colorless transparent fluorite, New Hampshire and New York produce bright green fluorite, and Columbia produces green fluorite. Colorless transparent fluorite crystals are produced in Ontario, Canada. Cornwall, England, produces white, blue, violet, reddish brown fluorite. Namibia produces grandmother green fluorite. Almost all provinces and regions in China have found fluorite resources, of which gem fluorite is mainly distributed in Zhejiang, Anhui, Jiangxi, Fujian, Henan, Hubei, Hunan, Guangxi, Sichuan, Guizhou, Qinghai, Xinjiang and other places.