Is this shark tooth fresh or fossilized?

posted: 04/11/12
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Shark Teeth
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People are fascinated by shark teeth, and often it's a case of the bigger, the better. While little fangs can be cheap, quirky souvenirs, larger samples are generally for more serious connoisseurs. Big shark teeth, like those of the extinct megalodon sharks, have a much heftier bottom line — they can set you back a few thousand dollars a pop.

Sharks shed their teeth constantly, so divers and beachcombers can find samples that are anywhere from a few days to thousands of years old. You can even find fossilized shark teeth in sedimentary rocks on dry land that used to be covered in prehistoric ocean. Most of the time, the shark teeth you find in gift shops have fossilized through a process called permineralization.

After sinking to the sandy ocean floor, shark teeth quickly become buried in sediments and start to absorb the mineral cocktail surrounding them. Different minerals turn shark teeth different colors as the minerals seep into their pores. Silica and calcite commonly do the trick, but depending on the specific ingredients in a shark tooth's landing pad, the final fossil can range from black to brown to gray. Some specimens even come in reddish, greenish or bluish hues.

A living shark's teeth are white, but if you find a whitish shark tooth on the beach, it's not necessarily fresh. In the right mix of sediments, fossilized teeth can stay close to their original color.

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