Pearl Formation
A pearl forms when an irritant enters the mollusk and is coated with layers of nacre. The irritant can be a particle or organism from the water. In cultured pearls,
the irritant is a piece of tissue or a mother-of-pearl bead that is surgically inserted. Usually, tissue is inserted
for a freshwater oyster and a round bead is inserted for a saltwater oyster (also called nucleating). Nacre is made
up of aragonite and conchiolin. Aragonite is a mineral arranged in flat hexagonal crystals and conchiolin is a type
of protein that is interwoven with the layers of aragonite. The thickness of the nacre affects the luster of the pearl.
References
American Gem Society. "About Pearls." About Pearls | Types of Pearls. American Gem Society, n.d. Web. 1 Dec. 2015.
"How Pearls Form." How Pearls Form. American Museum of Natural History, n.d. Web. 1 Dec. 2015.
The Pearl Market. "How Pearls Are Formed." How Pearls Are Formed. How Cultured Pearls Are Made. The Pearl Market, n.d. Web. 1 Dec. 2015.
Picture Sources:
hannahbethdean.wordpress.com
allaboutpearls.net
karipearls.com
pearl-guide.com