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Imitation Pearl
Imitation pearls are man-made ''faux'' pearls. They are not to be confused with cultured pearls, which are real pearls created through human intervention. Materials used to create imitation pearls include glass, plastic, and mollusc shells. As an alternative, some plastic beads are coated with a pearlescent substance to imitate the natural iridescence of nacre or mother of pearl. Types *Bathed pearl (also called Angel, Sheba, Mikomo, Kobe, Nikko, Sumo, Fijii, Aloha, or "improved cultured pearl") is a mother-of-pearl core coated with a mixture of plastic enamel, lead carbonate, mica, and titanium dioxide, then with a film of iridescent nylon. *Bohemian pearl is a cut and buffed mother-of-pearl protuberance. *Cotton pearl (also called "Utter Ethical pearl") is made merely from cotton and mica. *Glass pearl is a glass bead dipped or sprayed with pearlescent material, or hollow glass bead filled with pearlescent material. One variation is the Majorica pearl. Wax-filled pearl sim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Titanium Dioxide
Titanium dioxide, also known as titanium(IV) oxide or titania , is the inorganic compound derived from titanium with the chemical formula . When used as a pigment, it is called titanium white, Pigment White 6 (PW6), or Colour Index International, CI 77891. It is a white solid that is insoluble in water, although mineral forms can appear black. As a pigment, it has a wide range of applications, including paint, sunscreen, and food coloring. When used as a food coloring, it has E number E171. World production in 2014 exceeded 9 million tonnes. It has been estimated that titanium dioxide is used in two-thirds of all pigments, and pigments based on the oxide have been valued at a price of $13.2 billion. Structure In all three of its main dioxides, titanium exhibits Octahedral molecular geometry, octahedral geometry, being bonded to six oxide anions. The oxides in turn are bonded to three Ti centers. The overall crystal structures of rutile and anatase are tetragonal in symmetry ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cultured Pearl
Cultured pearls are pearls which are formed within a cultured pearl sac with human intervention in the interior of productive living molluscs in a variety of conditions depending upon the mollusc and the goals. Having the same material as natural pearls, cultured pearls can be cultivated in seawater or freshwater bodies. Over 95% of the pearls available on the market are cultured pearls. Development of a pearl A pearl is formed when the mantle tissue is injured by a parasite, an attack of a fish, or another event that damages the external fragile rim of the shell of a mollusk shell bivalve or gastropod. In response, the mantle tissue of the mollusk secretes nacre into the pearl sac, a cyst that forms during the healing process. Chemically speaking, this is calcium carbonate and a fibrous protein called conchiolin. As the nacre builds up in layers of minute aragonite tablets, it fills the growing pearl sac and eventually forms a pearl. Natural pearls are initiated in natu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hematite
Hematite (), also spelled as haematite, is a common iron oxide compound with the formula, Fe2O3 and is widely found in rocks and soils. Hematite crystals belong to the rhombohedral lattice system which is designated the alpha polymorph of . It has the same crystal structure as corundum () and ilmenite (). With this it forms a complete solid solution at temperatures above . Hematite occurs naturally in black to steel or silver-gray, brown to reddish-brown, or red colors. It is mined as an important ore mineral of iron. It is electrically conductive. Hematite varieties include ''kidney ore'', ''martite'' ( pseudomorphs after magnetite), ''iron rose'' and ''specularite'' ( specular hematite). While these forms vary, they all have a rust-red streak. Hematite is not only harder than pure iron, but also much more brittle. The term ''kidney ore'' may be broadly used to describe botryoidal, mammillary, or reniform hematite. Maghemite is a polymorph of hematite (γ-) with the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lobatus Gigas
''Aliger gigas'', originally known as ''Strombus gigas'' or more recently as ''Lobatus gigas'', commonly known as the queen conch, is a species of large sea snail, a marine gastropod mollusc in the family of true conches, the Strombidae. This species is one of the largest molluscs native to the Caribbean Sea, and tropical northwestern Atlantic, reaching up to in shell length. ''A. gigas'' is closely related to the goliath conch, ''Titanostrombus goliath'', a species endemic to Brazil, as well as the rooster conch, ''Aliger gallus''. The queen conch is herbivorous. It feeds by browsing for plant and algal material growing in the seagrass beds, and scavenging for decaying plant matter. These large sea snails typically reside in seagrass beds, which are sandy plains covered in swaying sea grass and associated with coral reefs, although the exact habitat of this species varies according to developmental age. The adult animal has a very large, solid and heavy shell, with knob- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coral
Corals are colonial marine invertebrates within the subphylum Anthozoa of the phylum Cnidaria. They typically form compact Colony (biology), colonies of many identical individual polyp (zoology), polyps. Coral species include the important Coral reef, reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton. A coral "group" is a colony of very many cloning, genetically identical polyps. Each polyp is a sac-like animal typically only a few millimeters in diameter and a few centimeters in height. A set of tentacles surround a central mouth opening. Each polyp excretes an exoskeleton near the base. Over many generations, the colony thus creates a skeleton characteristic of the species which can measure up to several meters in size. Individual colonies grow by asexual reproduction of polyps. Corals also breed sexually by spawning: polyps of the same species release gametes simultaneously overnight, often around a full moon. Fertilized eggs form ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isinglass
Isinglass ( ) is a form of collagen obtained from the dried swim bladders of fish. The English word origin is from the obsolete Dutch ''huizenblaas'' – ''huizen'' is a kind of sturgeon, and ''blaas'' is a bladder, or German ''Hausenblase'', meaning essentially the same. The bladders, once removed from the fish, processed, and dried, are formed into various shapes for use. It is used mainly for the Clarification (wine), clarification or fining of some beer and wine. It can also be cooked into a paste for specialised Fish glue, gluing purposes. Although originally made exclusively from sturgeon, especially Beluga (sturgeon), beluga, in 1795 an invention by William Murdoch facilitated a cheap substitute using cod. This was extensively used in United Kingdom, Britain in place of Russian isinglass, and in the US hake was important. In modern British brewing all commercial isinglass products are blends of material from a limited range of tropical fish. Foods and drinks file:T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sintering
Sintering or frittage is the process of compacting and forming a solid mass of material by pressure or heat without melting it to the point of liquefaction. Sintering happens as part of a manufacturing process used with metals, ceramics, plastics, and other materials. The atoms/molecules in the sintered material diffuse across the boundaries of the particles, fusing the particles together and creating a solid piece. Since the sintering temperature does not have to reach the melting point of the material, sintering is often chosen as the shaping process for materials with extremely high melting points, such as tungsten and molybdenum. The study of sintering in metallurgy, metallurgical powder-related processes is known as powder metallurgy. An example of sintering can be observed when ice cubes in a glass of water adhere to each other, which is driven by the temperature difference between the water and the ice. Examples of pressure-driven sintering are the compacting of snowfa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Majorica Pearl
Majorica is a Spanish company that manufactures hand-made pearls called Majorica pearls. Now based in Majorca, the company was founded in 1890 in Barcelona. In 1990, ''Gems & Gemology'' described Majorica pearls as "the most widely marketed and meticulously manufactured imitation earltoday". Production Majorica imitation pearls are man-made on solid balls, likely made of glass, that are coated with a proprietary coating that is made in part from fish scales. The coated nuclei are then dried and polished, and then dipped in a chemical (possibly cellulose acetate and cellulose nitrate Nitrocellulose (also known as cellulose nitrate, flash paper, flash cotton, guncotton, pyroxylin and flash string, depending on form) is a highly flammable compound formed by nitrating cellulose through exposure to a mixture of nitric acid and ...) to harden the surface and guard against discoloration, chipping, and peeling. References Pearls Spanish brands {{Spain-company-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mica
Micas ( ) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into fragile elastic plates. This characteristic is described as ''perfect basal cleavage''. Mica is common in igneous and metamorphic rock and is occasionally found as small flakes in sedimentary rock. It is particularly prominent in many granites, pegmatites, and schists, and "books" (large individual crystals) of mica several feet across have been found in some pegmatites. Micas are used in products such as drywalls, paints, and fillers, especially in parts for automobiles, roofing, and in electronics. The mineral is used in cosmetics and food to add "shimmer" or "frost". Properties and structure The mica group comprises 37 phyllosilicate minerals. All crystallize in the monoclinic system, with a tendency towards pseudohexagonal crystals, and are similar in structure but vary in chemical composition. Micas are translucent to opa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pearl
A pearl is a hard, glistening object produced within the soft tissue (specifically the mantle (mollusc), mantle) of a living Exoskeleton, shelled mollusk or another animal, such as fossil conulariids. Just like the shell of a mollusk, a pearl is composed of calcium carbonate (mainly aragonite or a mixture of aragonite and calcite) in minute crystalline form, which has deposited in concentric layers. More commercially valuable pearls are perfectly round and smooth, but many other shapes, known as baroque pearls, can occur. The finest quality of natural pearls have been highly valued as gemstones and objects of beauty for many centuries. Because of this, ''pearl'' has become a metaphor for something rare, fine, admirable, and valuable. The most valuable pearls occur spontaneously in the wild but are extremely rare. These wild pearls are referred to as ''natural'' pearls. ''Cultured'' or ''farmed'' pearls from Pinctada, pearl oysters and freshwater mussels make up the majority o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lead Carbonate
Lead(II) carbonate is the chemical compound with the chemical formula . It is a white, toxic solid. It occurs naturally as the mineral cerussite. Structure Like all metal carbonates, lead(II) carbonate adopts a dense, highly crosslinked structure consisting of intact and metal cation sites. As verified by X-ray crystallography, the Pb(II) centers are seven-coordinate, being surrounded by multiple carbonate ligands. The carbonate centers are bonded bidentate to a single Pb and bridge to five other Pb sites. Production and use Lead carbonate is manufactured by passing carbon dioxide into a cold dilute solution of lead(II) acetate, or by shaking a suspension of a lead salt more soluble than the carbonate with ammonium carbonate at a low temperature to avoid formation of basic lead carbonate. : Lead carbonate is used as a catalyst to polymerize formaldehyde to poly(oxymethylene). It improves the bonding of chloroprene to wire. Regulations The supply and use of this compound is re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
