The chemical composition of the crystal is silicon dioxide (SiO2), pure when the formation of colorless and transparent crystals, when containing trace elements Al, Fe, etc., to produce different colors, such as smoke, purple, yellow, etc.. Irradiated trace elements to form different types of color heart, resulting in different colors, such as purple, yellow, teal, pink and so on.
[crystal].
Luster: glassy luster, fracture resin luster
Transparency: translucent or transparent
Crystal system: tripartite crystal system
Fracture: shell-shaped
Hardness: 7
Specific gravity: 2.22-2.65
Refractive index: 1.544-1.553
Birefringence: 0.009
Dispersion: 0.013
[Classification].
According to the different colors of crystals, inclusions characteristics and special optical effects, crystals can be divided into the following varieties:
① According to the color category
colorless crystals, yellow crystals, amethyst, pink crystals (hibiscus stone), tea crystals (smoke crystal), green crystals and so on.
② classified by inclusions
hair crystal: common hair crystal varieties of gold hair crystal, black hair crystal, green hair crystal, white hair crystal, red hair crystal, blue hair crystal;
Ghost crystals: common varieties of red ghost, white ghost, green ghost, multi-colored ghost crystals and so on;
Rabbit hair crystals: they can be categorized into red rabbit hair crystals and yellow rabbit hair crystals.
In addition to appeal to these inclusions formed by the crystal varieties, but also visible titanium crystal, strawberry crystal, water gall crystal, super seven crystal varieties.
③Other varieties
Quartz cat's eye, starlight hibiscus stone, rainbow crystals and so on.
[origin].
The endogenous deposits of crystals are pegmatite-type, hydrothermal-type and skarn-type; exogenous deposits are commonly found in alluvial mines. Gem-quality crystals are mainly produced in crystal caves or pegmatite veins, almost all over the world have crystal output. Such as Madagascar, Zambia, Brazil, Germany, Russia, Myanmar, Afghanistan and so on.
[Selection of crystals
①Color
Crystal color evaluation of the highest standard is bright and beautiful, not with gray, black, brown and other shades. Pink crystal, the color to pink is good; amethyst, the color is required to bright purple, pure and not black; citrine, the color does not contain green, lemon tones, to golden orange is good.
② purity
The higher the clarity of the crystal, the better, try to avoid having more obvious inclusions in the crystal.
③Impurities
If the crystal internal impurities in the shape of legendary figures, such as constellations, zodiac signs and other values may be higher than the same color and clarity of the crystal.
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