First, the physical and chemical characteristics of turquoise
Turquoise usually presents a dense block, kidney, stalactite, and hull-like aggregates, especially with a unique sky blue or "turquoise color" that makes it easy to see at a glance. Its physical and chemical properties are as follows:
(1) Chemical composition:
An aqueous copper aluminate mineral having a molecular formula of CuAl6(PO4)4(OH)8·5H2O. The theoretical component is P2O5
34.12%, AL2O336.84%, CUO9.57%, H2O19.47%. The turquoise produced by nature is quite different from the theoretical one.
(2) Physical characteristics
Form: triclinic, cryptocrystalline, rare microcrystals, can only be seen under the microscope.
Fracture: shell-like to granular (related to the degree of pore system).
Hardness: The compactness of the block is 5-6, and the Mohs hardness is small.
Toughness: The white scorpion has small toughness and is easy to break, and the dense one has good toughness.
Streak: white or green.
Relative density: 2.4~1.9, the standard value is avoided. 76
Transparency: Usually opaque.
Gloss: The polished surface is greased glass and the grease is dull on the fracture.
Inclusions: often have black spots or black linear brown or other iron oxide wraps.
Refractive index: N8 = 1.65, NM = 1.62, NP = 1.61. Since turquoise is often a green aggregate, there is only one reading on the gem refractometer, with an average of about 1.62.
Birefringence: crystal birefringence (DR) is strong, DR=0.040. However, it is not shown in the gemological test.
Optical characteristics: crystal biaxial crystal positive light, 2Y=40. Gemological test data cannot be provided because turquoise is usually opaque.
Color: sky blue, very characteristic, so that it becomes a standard color - turquoise. The rest are dark blue, light blue, lake blue, blue green, apple green, yellow green, light yellow, light gray. Copper causes blue, iron can replace part of the aluminum in the chemical composition, making the turquoise green, and the water content also affects the blue hue.
Absorption spectrum: Under strong reflected light, two medium to weak blue regions of 432 nm and 420 nm absorption bands are occasionally seen, and sometimes ambiguous absorption bands are visible at 460 nm.
Luminescence: Fluorescence of yellowish green to blue under long ultraviolet light, short-wave fluorescence is not obvious. There was no obvious luminescence under X-ray irradiation.
Thermal properties: When exposed to heat, it usually bursts into pieces, turns brown, and appears green under flame.
Acid: It dissolves very slowly in hydrochloric acid.
Turquoise variety
Turquoise is usually classified by origin, color, luster, texture, structure and structure, and many classifications are more or less extended to the quality level of turquoise and thus have a hierarchical meaning.
(1) Classified by color:
A, blue turquoise (Blueturquoise): blue, opaque block, sometimes dark blue;
B, light blue turquoise (Palablueturquoise): light blue, opaque block;
C, Blue-green turquoise (Blue-green turquoise): blue-green, opaque block;
D, Green Turquoise (Green Turquoise): green, opaque block;
E, Yellow-green turquoise (Yellow-greenturquoise): yellow-green, opaque block;
F, Greenish turquoise (Greenishturquoise): light green, opaque block.
(2) According to structure, structure, gloss and texture:
A. Transparent turquoise: refers to transparent turquoise crystals. Very rare, only produced in Virginia, USA, after honing transparent gems weigh less than 1 carat;
B. Blocky turquoise: refers to dense blocky turquoise, which is bright in color, fine in texture, tough and smooth, and is the main material of jade carving, which is quite common;
C, tuberculous turquoise: refers to the shape of a spherical, ellipsoidal, grape-shaped, pincus-shaped turquoise, the size of the tuberculosis is very different;
D, blue turquoise: also known as "lace turquoise", refers to the turquoise formed by the presence of iron with a spider web pattern;
E, iron wire turquoise: refers to the surface of the turquoise with a fine iron black line;
F, porcelain turquoise: refers to the sky blue, the texture is dense and tough, the fracture is broken like a porcelain break, the unusual bright turquoise, the quality is good;
G, veined turquoise: refers to the veins that are veined and present in the broken zone of the surrounding rock;
H, variegated turquoise: refers to the speckled, star-like structure of turquoise due to the inclusion of kaolinite and limonite, the quality is poor;
I, face loose: refers to the texture is not strong turquoise, the fracture is granular, the hardness is small, can be scored with nails. Some blocks are available;
J, foaming: refers to the turquoise which is softer than the surface, which is inferior and cannot be used as jade carving material. But now this turquoise has been artificially colored and glued to become an optimized turquoise variety.
(3) According to the place of origin:
A. Turquoise in Hubei: It is produced in the turquoise of northwestern Hubei Province. It is called "Jingzhou Stone" or "Xiangyangdianzi". Hubei has a large production of turquoise and excellent quality. It is well-known in China and abroad, mainly distributed in Jixian, Zhushan and Daixi in the northwest of Hubei. In other places, the mine is located in the western end of the Wudang Mountains and in parts of the south of Hanshui.
B. Nishapur Turquoise: Produced in the Nishapur area on the Mount Ali Miesel in northern Iran. In ancient China, it was called "Returning to Dianzi", and Japan and other countries called "Oriental Turquoise".
C. Sinai Turquoise: Located on the Sinai Peninsula, it is the oldest turquoise mine in the world.
D. Turquoise in the United States: Produced in the southwestern states of the United States, especially Arizona.
According to the place of origin, there are also Egyptian turquoise, Chilean turquoise, Australian turquoise, and so on. However, some names of origins not only represent the place of origin, but also represent and indicate the quality level of turquoise, so these names also have a quality rating.
Denim Shirts,Denim Shirt Men,Denim Work Shirts,Mens Denim Shirt Sale
Shaoxing Shanhe garments co.,ltd , https://www.sx-sanhe.com