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| − | {{dablink|Mother of Pearl redirects here. For the novel, see [[Mother of Pearl (novel)]]}} | + | {{honor_header|3|1949|Nature<br>General Conference<br>2001 Edition}} |
| − | '''Nacre''', also known as '''mother of pearl''', is a naturally-occurring organic-inorganic composite.
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| − | [[Image:NautilusCutawayLogarithmicSpiral.jpg|thumb|right|225px|The iridescent nacre of a [[Nautilus]] ]]
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| − | == Description == | + | ==1. Have the Shell Honor. == |
| − | Nacre is composed of hexagonal platelets of [[aragonite]] ([[calcium carbonate]] (CaCO<sub>3</sub>) [[crystals]]) that are 10-20 µm wide and 0.5 µm thick, arranged in a continuous parallel lamina. The layers of platelets are separated by sheets of organic matrix that are composed of [[elastic]] [[biopolymers]] (such as [[chitin]], [[lustrin]] and [[silk]]-like proteins). This mixture of brittle platelets and the thin layers of elastic biopolymers makes the material strong and resilient. Strength and resilience are also likely to be due to adhesion by the "brickwork" arrangement of the platelets, which inhibits transverse crack propagation. This design at multiple-length sizes increases its toughness enormously, making it almost equivalent to that of [[silicon]].
| + | {{Ay prerequisite|Nature|Shells}} |
| | + | ==2. Define the term "mollusca" or "mollusk." == |
| | + | ==3. Learn the classification terms of mollusks, know the distinguishing characteristics of each, and become acquainted with several species under each class. == |
| | + | ==4 Distinguish between univalve and bivalve mollusks from the following considerations: == |
| | + | ===a. Shell === |
| | + | ===b. Mollusk body === |
| | + | ===c. Reproduction=== |
| | + | ===d. Movements=== |
| | + | ===e. Securing food=== |
| | + | ===f. Self-preservation=== |
| | + | ==5. Identify from shells or drawings and know the meaning of the following concho logical terms: == |
| | + | ===a. Valve === |
| | + | ===b. Apex === |
| | + | ===c. Aperture === |
| | + | ===d. Byssus === |
| | + | ===e. Foot === |
| | + | ===f. Mantel === |
| | + | ===g. Operculum=== |
| | + | ===h. Mother of pearl=== |
| | + | ===i. Epidermis=== |
| | + | ===j. Ribs=== |
| | + | ===k. Teeth=== |
| | + | ===l. Concentric lines=== |
| | + | ===m. Canal=== |
| | + | ===n. Spines=== |
| | + | ===o. Whorls=== |
| | + | ===p. Lips=== |
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| − | The [[iridescent]] appearance of the nacre is due to the fact that the thickness of the aragonite platelets are about 0.5 micrometres, which is comparable to the wavelength of visible light. This results in constructive and destructive [[interference]] of different wavelengths of light, resulting in different colors of light being reflected at different viewing angles.
| + | ==6. Explain the development of a shell. How long do mollusks live?== |
| | + | ==7. Give some facts about the life of a strombus pugilis (fighting conch) and explain why this shell is so named. == |
| | + | ==8. Explain the activities of the shipworm. == |
| | + | ==9. What accounts for the distribution of mollusks.== |
| | + | ==10. Name two mollusks that have no shells. == |
| | + | ==11. Find answers for the following interesting questions: == |
| | + | ===a. How are bivalve and univalve animals fastened to their shells? === |
| | + | ===b. How is shell color controlled? === |
| | + | ===c. What mollusk has four gills? === |
| | + | ===d. From what sea animal was India ink formerly made? === |
| | + | ===e. What mollusk spins a silken thread? === |
| | + | ===f. What shells were used for money by ancient tribes? === |
| | + | ===g. What shell is considered sacred by the Tibetans? === |
| | + | ===h. Purple dye of ancient times came from the secretion of what mollusk? === |
| | + | ===i. What is the source of pearls? How are they formed? === |
| | + | ==12. Name six commercial uses for shells. == |
| | + | ==13. Do one of the following: == |
| | + | ===a. Personally find and collect 40 species of shells representing the five classifications. List each shell as to the place and date it was found, common name, scientific name, and class. === |
| | + | ===b. Make a collection of 50 species of shells you have found, received, or purchased representing the five classifications. List each shell collected as follows: if personally found, give the information called for under letter "a" above; if received or purchased, give the name of the person from whom the shell was received, the habitat of the shell, the date of its acquisition, and its common name, scientific name, and class.=== |
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| − | Nacre is secreted by the [[epithelial]] [[cell (biology)|cells]] of the [[Mantle (mollusc)|mantle tissue]] of certain species of [[mollusk]]. In these mollusks, nacre is continually deposited onto the inner surface of the animal's shell (the [[iridescent]] ''nacreous layer'', commonly known as ''mother of pearl''), both as a means to smooth the shell itself and as a defense against [[parasite|parasitic organisms]] and damaging detritus.
| + | [[Category:Adventist Youth Honors Answer Book|{{SUBPAGENAME}}]] |
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| − | The iridescent inner layer is considered highly attractive by many cultures and is often used in making [[jewelery]] or as inlays in wood [[furniture]] and [[guitar]]s.
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| − | When a mollusk is invaded by a [[parasite]] or is irritated by a foreign object that the animal cannot eject, a process known as ''[[encystation]]'' entombs the offending entity in successive, concentric layers of nacre. This process eventually forms what we call [[pearl]]s and continues for as long as the mollusk lives.
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| − | Chief sources are the pearl [[oyster]], found in warm and tropical seas, primarily in [[Asia]]; [[freshwater pearl]] mussels, which live in many rivers of the [[United States]], [[Europe]], and [[Asia]]; and the [[abalone]] of [[California]], [[Japan]], and other [[Pacific Ocean|Pacific]] regions.
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| − | ==Decorative uses==
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| − | Both black and white mother of pearl are used for architectural purposes. The natural mother of pearl may be artificially tinted to almost any color.
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| − | Mother of pearl is also used to clad porcelain sinks. Mother of pearl tesserae may be cut into artistic shapes and be laminated to ceramic tile and surrounded by numerous coats of colored lacquer to create an artistic design. The lacquer and the mother of pearl are polished at the same time, creating a durable, glossy hard surface.
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| − | It is also available in thin laminated sheet form, allowing easy inlay and cladding work, and modern ceramic tiles.
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| − | Shirt buttons were once often made of mother of pearl, though plastic has largely replaced its use. Some of the finer-quality clothing companies (e.g., [[Lacoste (company)|Lacoste]] and [[Turnbull & Asser (company)|Turnbull & Asser]]) still use it, however.
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| − | Mother of pearl is a popular style watch dial also found in [[Rolex]] watches.
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| − | Key touches and various decorations on musical instruments such as [[saxophone]]s, [[trumpet]]s, [[violin]]s and [[guitar]]s are sometimes made of mother of pearl. Synthetic key touches made of [[Pyralin]] or similar imitation materials have been "affectionately" referred to as ''mother of toilet seat'' by musicians.
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| − | ===Tiles===
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| − | Small, hand-cut shapes with straight edges, called 'tesserae', are laminated to either a [[marble]] or a [[ceramic]] base. The tesserae are hand-placed and closely sandwiched together, creating an irregular mosaic or pattern (such as a weave). The laminated material is typically 1/16 of an inch thick.
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| − | ===Sheets===
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| − | Instead of using a marble or tile base, the mother of pearl tesserae are glued to a [[fiberglass]] mesh. The result is a lightweight material that offers a seamless installation, and there is no limit to the sheet size. Mother of pearl sheets may be used on interior floors, exterior and interior walls, countertops, doors and ceilings. Insertion into architectural elements, such as columns or furniture is easily accomplished.
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| − | ==Gallery==
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| − | <gallery>
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| − | image:nacre.jpg|A piece of nacre
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| − | image:Nacre_microscopic_structure.png|Microscopic structure of nacre—layers of aragonite platelets are separated by protein
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| − | Image:HoloscaphitesAmmonite.jpg|[[Fossilized]] [[Ammonite]] with nacre shell intact
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| − | </gallery>
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| − | ==References==
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| − | *Lin, A., and Meyers, M.A. (2005). Growth and structure in abalone shell, ''Materials Science and Engineering A'' '''390'''(Jan. 15):27–41 ([http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TXD-4DH2DRS-1&_coverDate=01%2F15%2F2005&_alid=256050522&_rdoc=1&_fmt=&_orig=search&_qd=1&_cdi=5588&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=f4efd0a3d7cf3b4a0b8f9861cff4514d ])
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| − | *Mayer, G. (2005). [http://www.sciencemag.org/cgi/content/abstract/310/5751/1144 Rigid biological systems as models for synthetic composites]. ''Science'' '''310''':1144–1147
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| − | *{{cite journal | quotes=no|author = Ortiz C. ''et al.''|year=September 2005|title = Nanoscale morphology and indentation of individual nacre tablets from the gastropod mollusc ''Trochus niloticus''|journal= J. Mater. Res.|volume= 20|issue=9}} [http://web.mit.edu/cortiz/www/Ben/BenPaperRevisedFinal.pdf pdf file on line]
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| − | ==See also==
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| − | {{Wiktionary}} | |
| − | * [[Ammolite]]
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| − | [[Category:Mollusc products]]
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| − | [[Category:Pearls]]
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| − | [[de:Perlmutt]]
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| − | [[es:Nácar]]
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| − | [[fr:Nacre]]
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| − | [[nl:Parelmoer]]
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| − | [[pl:Masa perłowa]]
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| − | [[pt:Madrepérola]]
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| − | [[sv:Pärlemor]]
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| − | [[tr:Sedef]]
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| − | [[vi:Xà cừ (vật liệu)]]
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