Turquoise physical properties
Turquoise is a unique and historically significant gemstone known for its vibrant blue color. Here are some of its physical properties: Crystal System: Turquoise typically forms in a triclinic system, but it is mostly cryptocrystalline, with microcrystals only visible under a microscope. Fracture: It exhibits a shell-like to granular fracture pattern, which depends on the development of its internal pore structure. Hardness: The hardness of turquoise varies between 5 and 6 on the Mohs scale, though this can depend on how compact or dense the material is. Toughness: Some varieties, like the "white scorpion," have low toughness and are prone to breaking, while denser types show better durability. Streak: The streak of turquoise is usually white or green. Specific Gravity: Its relative density ranges from 2.4 to 1.9, though the standard value is often around 2.6. Transparency: Turquoise is generally opaque, though some rare specimens may show slight translucency. Luster: When polished, turquoise has a greasy glassy luster, while the fracture surface appears dull. Inclusions: It often contains black spots, linear brown streaks, or other iron oxide inclusions that give it a distinctive appearance. Refractive Index: The refractive index values are Nα = 1.65, Nβ = 1.62, and Nγ = 1.61. However, since turquoise is typically an aggregate, most gemological instruments will only register an average of about 1.62. Birefringence: Although turquoise has a strong birefringence (DR = 0.040), it is not typically detectable in routine gem tests due to its opacity. Optical Properties: Turquoise is a biaxial crystal with positive optic sign, and the angle between the two optic axes is approximately 40°. Due to its opacity, gemological testing is limited. Color: The most iconic color of turquoise is a vivid sky blue, which has become a standard reference point for the stone's name. Other colors include dark blue, light blue, lake blue, blue-green, apple green, yellow-green, light yellow, and light gray. The blue color comes from copper, while iron can replace aluminum in the chemical formula, resulting in a greenish tone. Water content also influences the hue. Absorption Spectrum: Under strong reflected light, turquoise may show weak absorption bands at 432 nm and 420 nm, and sometimes faint absorption at 460 nm. Fluorescence: It exhibits a yellowish-green to blue fluorescence under long-wave ultraviolet light, though short-wave UV shows less response. No significant luminescence is observed under X-ray. Thermal Properties: When exposed to heat, turquoise tends to crack and turn brown, but it may appear green when placed near a flame. Chemical Reactivity: Turquoise reacts slowly with hydrochloric acid, dissolving very gradually. Turquoise has been prized for centuries for its beauty and cultural significance, making it one of the most recognizable and cherished gemstones in the world. Butterfly Valve,Groove Butterfly Valve,Turbine Butterfly Valve,Cast Iron Butterfly Valve Zhengzhou guan hao yong International Trade Co., , https://www.homepipes.com