Introduction to the article
In some mollusks, pearl is a dense condensate, which is formed by the polymerization of true nacre around foreign particles, which are not attached to the shell or under the shell. It has various shapes, but the most typical ones are round and pear-shaped, with various colors, but they are usually white or light, with different degrees of luster, and can be used for decoration or medicine. ?
Pearl's English name is Pearl, which evolved from Latin Pernulo. Its other name is Margaret, which comes from ancient Persian Sanskrit, meaning "son of the sea".
As early as ancient times, when primitive humans were foraging by the sea, they found white pearls with colorful auras and were attracted by their crystal splendor. Since then, pearls have become people's favorite ornaments and have been passed down to this day.
The main aquaculture areas of freshwater pearls in China are Zhuji, Changde, Suzhou, Jiangxi, Hubei and Anhui. There are five kinds of pearls: white, red, yellow, black and variegated, and most of them are opaque. Zhu Zhen, Zhu Zhen, mussel pearl, pearl, lotus pearl.
The inorganic components of pearls are mainly calcium carbonate and magnesium carbonate, accounting for more than 9 1%, followed by silica, calcium phosphate, Al2O3 and Fe2O3.
The organic matter in pearls contains 17 amino acids such as aspartic acid, threonine, serine, glutamic acid, glycine, alanine, cystine, valine, methionine, isoleucine, leucine, tyrosine, phenylalanine, histidine, arginine and proline. In addition, it also contains more than 30 kinds of trace elements, taurine, rich vitamins and peptides.
Pearl has various shapes, such as round, pear-shaped, egg-shaped, teardrop-shaped, button-shaped, arbitrary shape, etc., among which round is the best. Not an isotropic body. Colors are white, pink, light yellow, light green, light blue, brown, lavender, black and so on. , mainly white.
White stripes. It has typical pearl luster, soft luster and rainbow color. Transparent to translucent. Refractive index 1.530- 1.686, birefringence: aggregate is unmeasurable. There is no dispersion. The hardness is 2.5-4.5. The density of natural freshwater pearls is generally 2.66-2.78g/cm3, which varies from place to place.
No cleavage. Good toughness. White pearls are light blue to light yellow under short-wave ultraviolet irradiation; Yellow and golden pearls are yellow-green, green-brown to dark brown; Black pearls are usually pink to orange-red; There is yellow-white fluorescence under X-ray. Foam in hydrochloric acid. ?
Natural pearls are spherical, oval, irregular spherical or rectangular with a diameter of 1 ~ 6mm. The surface is white, yellowish white, light pink, light blue, etc. , with beautiful color and smoothness. Most decorated pearls have holes in the middle. It's hard and difficult to break, and the section has a layered feeling. It crackled with fire. No gas, slightly salty.
The shape of cultured pearls is similar to that of natural pearls, but the surface gloss is weak. There are round sand or concha Haliotidis fragments in the center of the section, and a thin layer of real pearls on the surface. Only the nacre is used as medicine. No gas, slightly salty. However, the appearance of Hepu ecological pearls has greatly improved the quality of cultured pearls.