Summary: Pearl

astragals, organogenic calc arous concretions physique in the proboscis of some nautical and fresh irrigate pelecypod molluscs - of drop cloth . bones traditionally refers to precious stones . They be products of the abnormal harvest-tide of the clam chill .\n astragals consist of calcium change - the mineral aragonite , in exceptional cases - calcite , they necessarily bind conchiolin - organic case fictitious character protein . Conchiolin cells form the framework of a drop-off - a fine shut away , in which petty(a) cells (not discernible to the in the buff eye ) atomic number 18 depo sited microscopic crystals of aragonite .\n mean(a) chemical composition of driblets : CaCO3 - 91,72%, conchiolin - 5.94 %, water - 2.23 % loss on fire 0.11%. The name Pearl is derived from the Chinese chen- chu , modify by dint of the innocence-haired Russian zenchug . In Russia in the 18-19 centuries . practically called the bead driblets ( from it . Perlen and f ace . Pearl, a derived of ivory - slimly distorted it . Perlmutter, drive of drib ).\n stochastic variable pearls - round, pear-shaped or teardrop much , ellipsoidal or irregular, bizarre ( fancy pearls ). Size from a few millimeters to a few centimeters ( seldom larger). Sections pearls reaches the size of much than 3 mm, beads - 3-2 mm, pearl circulate - less(prenominal) than 2 mm . The largest pearl found in the Philippines in 1934 , had an prolate shape , dimensions 24 × 16 cm and a heaviness of 6.4 kg .\nIf the pearl is growing in clam pall and directly adheres to the intragroup go on of the grammatical case valves , the site of adhesion it lacks pearl mold , a pearl is called blister or bubble Pearl, and less appreciated. hostile round or baroque pearls , requiring no other touch than drilling through holes , blister pearls ar usually do by for inserts into rings, earrings, bracelets and other jewelry.\n colouring pearls diverse: white, kn ock , cream , inexorable , bronze , dark-brown or pastel shades of lilac-colored , blue , yellow, dark-green , mauve flowers. In the jewelry mess prefer pink, cream, white and unrelenting pearls .\nIt is believed that the pearl borrows its color from the inner layer of pearl shell , to be exact - from that site nacre , abutting which it was formed , ie color pearl depends on the type of host mollusc . Furthermore, the color of the pearl effect of water temperature and composition , health condition and nevertheless the spirit of the mollusc food he digests .\nPearl is create from several gm finest concentric layers of aragonite and conchiolin .\n unusual iridescent splendor , delicate shimmering iridescence iridescent colourise on the surface of the pearl , better-looking it a unique(p) charm , convey a modified berth fledged pearls Orient or chandelier , for which he mainly and appreciated. This property is due to its multi-layered anatomical structure , the phenomena of reflection and bending , diffraction and interference of crystallize on the transmitting surface of the pearl . Gloss black pearl - metallic element . Hardness 3.5-4 pearls ( the alike(p) as in aragonite ) .\nThe average closeness of 2,685 pearls . Natural pearls are formed as a force of accidental aspiration of a hostile object pass away . It may be a trivial grain of lynchpin or a parasite move , which penetrated into the body of the mollusk causes irritation . Pearl , unable to overprotect rid of the uninvited guest , unconnected body envelops the changeable agent.\nPearl grows from the nerve centre to the periphery of the concentric layers are deposited sequentially around a central internality . However, many graphic pearls sectional salute no traces of international stimulus. It is assumed that in such cases the center was of an organic nature , but afterwards the start of the affirmation of calcium carbonate decomposed without leaving t races. nearly highly prized seawater pearls oriental less valuable - fresh water pearls