AY Honors/Shells - Advanced/Answer Key

2005-09-08T06:11:28Z

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[[image:nacre.jpg|thumb|A piece of nacre]]
'''Nacre''', also known as '''mother of pearl''' or '''sadaf''', is an organic mixture of [[calcium carbonate]] (CaCO<sub>3</sub>) in the form of platy crystals of [[aragonite]] and [[conchiolin]] (a [[scleroprotein]]).

Nacre is secreted by the [[ectoderm|ectodermic]] [[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.

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.

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.

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==

Tiles: 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.

Sheets: 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.

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 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.

It is also available in thin laminated sheet form, allowing easy inlay and cladding work, and modern ceramic tiles.

==Reference==

*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 ])

== See also ==
{{Wiktionary}}
* [[Ammolite]]

[[Category:Animal products]]
[[Category:Molluscs]]
[[Category:Gemstones]]

[[de:Perlmutt]]
[[pl:Masa perłowa]]

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AY Honors/Shells - Advanced/Answer Key