AY Honors/Shells - Advanced/Answer Key

2007-12-07T23:37:00Z

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{{redirect|Mother of Pearl|the novel|Mother of Pearl (novel)}}
'''Nacre''', also known as '''mother of pearl''', is an organic-inorganic [[composite material]] produced by some [[mollusk]]s. It is strong, resilient, and [[Iridescence|iridescent]]. [[Pearl]]s and the inside layers of an oyster shell are made of nacre.
[[Image:NautilusCutawayLogarithmicSpiral.jpg|thumb|right|225px|The iridescent nacre of a [[Nautilus]] ]]

==Description==
Nacre is composed of hexagonal platelets of [[aragonite]] ([[calcium carbonate]] (CaCO3) [[crystals]]) 10-20 µm wide and 0.5 µm thick, arranged in a continuous parallel lamina. These layers are separated by sheets of organic matrix composed of [[Elasticity (physics)|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]].

Nacre appears [[iridescent]] because the thickness of the aragonite platelets 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.

Nacre is secreted by the [[epithelial]] [[cell (biology)|cells]] of the [[Mantle (mollusc)|mantle tissue]] of some species of [[mollusk]]. The nacre is deposited onto the inner surface of the shell, the iridescent ''nacreous layer'', commonly known as ''mother of pearl''. This smooths the shell and defends against [[parasite]]s and damaging detritus by entombing them in successive layers of nacre, forming a [[pearl]]. The process is called is ''[[encystation]]'' and continues while the mollusk lives.

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.

== Decorative uses ==
[[Image:Istanbul.Topkapi046.jpg|thumb|right|200px|<center> Inlay with nacre tesserae </center> Bagdad pavilion, Topkapı Palace, Istanbul, Turkey ]]
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. Mother of pearl [[:wikt:tessera|tesserae]] may be cut into shapes and laminated to a ceramic tile or marble 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. The tesserae are then lacquered and polished creating a durable, glossy hard surface.

Instead of using a marble or tile base, the mother of pearl tesserae can be 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.

=== Clothes & accessories ===
Mother of pearl buttons can be found on a variety of clothing such as shirts, skirts and coats. Nacre is also used as a decorative feature of watch faces and jewelry. It is very valued.

=== Musical instruments ===
Key touches and various decorations on musical instruments such as [[saxophone]]s, [[trumpet]]s, [[violin]]s, [[banjos]], and [[guitar]]s are sometimes made of mother of pearl. It is used as inlays on many guitar fretboards e.g. the [[Gibson J-200]]. Synthetic key touches made of [[Pyralin]] or similar imitation nacre materials have been affectionately referred to as ''mother of toilet seat'' by musicians.

==References==
* {{cite journal
| first = A.
| last = Lin
| coauthors = Meyers, M.A.
| date = 2005-01-15
| title = Growth and structure in abalone shell
| journal = Materials Science and Engineering A
| volume = 390
| pages = 27–41
| url = 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
| doi = 10.1016/j.msea.2004.06.072
}}
* {{cite journal
| first = G.
| last = Mayer
| year = 2005
| url = http://www.sciencemag.org/cgi/content/abstract/310/5751/1144
| title = Rigid biological systems as models for synthetic composites
| journal = Science
| volume = 310
| pages = 1144–1147
}}
* {{cite journal
| last = Bruet
| first = B.
| coauthors = ''et al.''
| year = 2005
| month = September
| title = Nanoscale morphology and indentation of individual nacre tablets from the gastropod mollusc ''Trochus niloticus''
| journal = J. Mater. Res.
| volume = 20
| issue = 9
| url = http://web.mit.edu/cortiz/www/Ben/BenPaperRevisedFinal.pdf
| doi = 10.1557/JMR.2005.0273
}}

==See also==
{{commons|Category:Mother of pearl}}
{{Wiktionary}}
* [[Ammolite]]

[[Category:Mollusc products]]
[[Category:Pearls]]

[[bg:Седеф]]
[[da:Perlemor]]
[[de:Perlmutt]]
[[eo:Perlamoto]]
[[es:Nácar]]
[[fr:Nacre]]
[[he:אם הפנינה]]
[[it:Madreperla]]
[[lt:Perlamutras]]
[[nl:Parelmoer]]
[[pl:Masa perłowa]]
[[pt:Madrepérola]]
[[ru:Перламутр]]
[[sv:Pärlemor]]
[[vi:Xà cừ (vật liệu)]]

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AY Honors/Shells - Advanced/Answer Key