Pearl, an ancient organic gem, is mainly produced in mollusks such as Pinctada and Pinctada. Pearl is a mineral bead containing calcium carbonate produced by the endocrine function of shellfish, which is composed of a large number of tiny aragonite crystals. Rich in variety, different in shape and colorful.
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.
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.
chemical composition
The inorganic components of pearls are mainly calcium carbonate and magnesium carbonate, accounting for more than 9 1%, followed by silica and calcium phosphate.
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.
Appearance characteristics
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 to 1.686, birefringence: aggregate is unmeasurable. There is no dispersion. The hardness is 2.5 to 4.5. The density of natural freshwater pearls is generally 2.66 to 2.78 g/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.
Trait recognition
Natural pearls are spherical, oval, irregular spherical or rectangular with a diameter of 1 to 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 grains or concha Haliotidis fragments in the middle of the section, and there is 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.
Collection and treatment
This product is a granular pearl obtained from mussels.
It is produced all year round, usually in June, diving to the bottom of the sea, taking mussels from aquatic plants or stones and pearls from them. Meat is edible.
Both Pharmacopoeia and Dictionary of Traditional Chinese Medicine show that pearls have the functions of calming nerves, improving eyesight, removing toxic substances and promoting granulation. Modern research also shows that pearls have unique functions in improving immunity, delaying aging, removing spots and whitening skin, and supplementing calcium.