News

Have any fossils been found inside precious gems?

Posted September 02, 2008 11:00 pm

Hope Babowice

"Have any fossils been found inside precious gems?" asked Eli Haworth, 9, a fourth-grader at Cumberland School in Des Plaines.

Fossils are rocks with imprints or evidence of ancient plants or animals. These rocks are millions of years old.

Here's how a fossil typically forms. The object or fragment floats to the bottom of a lake or river bed. Under normal situations, old bones and plants decay. When fossils form, the object does not decay because chemical elements in the surrounding mud and rock block decaying from occurring. Over millions of years, rock sediments build up and compact the object. Minerals from the sediments leach into the object, changing it into sedimentary rock.

A fossil can be a plant or animal that has transformed into rock. Some fossils show an animal's tracks that were made when it walked or swam, or are evidence of an animal's burrow. There are fossils that are imprints of ancient plants or animals. Some fossils show a different kind of evidence - what an animal ate. Fossilized animal droppings is called a coprolite. All fossils are a kind of historical document - a way for people today to learn about the Earth's past by observing evidence of plants and animals lived a very long time ago.

Ancient animals and plants might be preserved in a few different ways. A bone, tooth, a log or a leaf might be preserved when minerals turn the matter into rock. In another process, all of the original matter is destroyed, but the shape is preserved. This can either be a mold of the object or it can be a cast - when the form of the object is preserved and is filled with a mineral.

There are materials that create fossils that are not rock. Peat bogs have preserved woolly mammoths and humans in perfect form. You can see the body of a 2,000-year-old man, called "Lindow Man," at the British Museum in London. His ancient remains were discovered completely preserved in a peat bog in England. Amber, a fossilized tree resin, can contain insects, feathers, plants or animals that go back more than 30 million years. Amber, which is not a mineral, is considered a gemstone.

The official gemstone of Australia is opal, a mineraloid with high water content. Opal has been found to replace the original structure of a fossilized objects, making them fossilized gemstones. Mollusks, sea shells, dinosaur bones and wood are objects that can become fossils with opalization. Can a fossil be found inside a precious gem? Michael Henderson, paleontologist and curator at the Burpee Museum of Natural History in Rockford, said, "No fossils have been found in precious gems such as diamonds, rubies, emeralds, etc. These gemstones form deep underground in environments where fossilization would be impossible."

However, many types of fossils are made into jewelry.

"Jet, often carved or made into jewelry, is a form of fossilized wood," Henderson said. "A beautiful iridescent material called ammolite is made from the fossil remains of a type of cephalopod mollusk called an ammonite. And even fragments of dinosaur bone are sometimes polished and incorporated into jewelry."