Split ammonite fossil earrings in 14K gold fill.

Split ammonite fossil earrings in 14K gold fill.

Since today is National Fossil DayTM, I wanted to do a bit of a show-and-tell. I love working with fossils in my jewelry, and a number of them have ended up on here, so I thought I’d do a brief overview of the ones I use most often


Fossils are fascinating. Just think for a minute about the intricacy of ancient life that they preserve. They’re like little time capsules.

Orthoceras fossils in sterling silver with garnet.

Orthoceras fossils in sterling silver with garnet.

And some are simply beautiful. The mathematical spirals of the ammonites and their sometimes shimmering exteriors, the oddly modern sleekness of a monochromatic orthoceras… even without knowing their history they can be extremely evocative..


Disclaimer-these are generally index fossils-comparatively common ones that can be used to help dates sites with rarer specimens but not ones that ought to go to a museum except in the gift shop-don’t just nab fossils from National Parks!


Ammonites: Ammonite can refer to any of various species of long extinct cephalopods. They were a family of carnivorous species that lived in the seas from 300-65 million years ago. Their fossils are fairly common and show a great deal of variation-both among species and the way in which they were fossilized.


Ammolite: In a small part of central North America ammonites were fossilized then covered in dense enough material that calcite didn’t replace the iridescent on the outside of the shells, so it’s actually opaque and thick enough to cut into gems. The thickness of that layer determines the colors of the ammolite, which can run though the entire spectrum.


Brachiopods: They’re marine animals with top and bottom shells, rather than left and right like bivalves. Some species are still alive, though they were much more common in the past. I work with brachiopods from the Spiriferida order (preferably mucrospirifers). They have a long hinge and often a deep fold in the center and are sometimes called butterfly shells. These flourished during the mid-Devonian Period, so odds are they’re around 385 million years old.


Fossil Jasper: It’s basically fossilized sea floor. It has bits and pieces of whatever fell to the bottom. I normally run across it as looking like pink and grey granite with tiny pink circles from crinoids. Crinoids are animals that anchor to the sea floor. They’re sometimes called sea lilies. Most species have gone extinct over the millennia, but some species still exist.


Fossilized Coral: Fossilized corals are found worldwide. The body parts of the coral had slowly been replace with agate, so sometimes it’s called agatized coral. The state stone of Michigan is Petoskey stone, a type of fossilized coral with a hexagonal pattern.


Orthoceras in brass and copper.

Orthoceras in brass and copper.

Orthoceras: They’re a genus of extinct cephalopods. Orthoceras means straight horn. They were soft bodied creatures that lived in the newest segment of the shell. Periodically they would grow a separating wall close off the too small part of the shell. We can still see these divisions in their fossils. They first emerged nearly 500 million years ago and went extinct nearly 200 million years ago. (They existed from the Ordovician through the Triassic. They had a 200 million year overlap with their younger cephalopod cousins, the ammonites.)


Trilobite in copper and silver.

Trilobite in copper and silver.

Trilobites: Extinct arthropods. Extinction doesn’t mean failure though! They survived for over 250 million years-that’s longer than the dinosaurs. Their fossils have been found all over the world. However, a most of the fossils are of molted exoskeletons, not actually the creatures themselves.


Turritella Agate: It’s a bit of a misnomer. The shells in turritella agate are elimia, extinct freshwater snails from the Eocene. (Turritella were similarly shaped saltwater snails.) Elimia flourished in a warmer, wetter world than ours, millions of years after the dinosaurs went extinct.

Dinosaur bone, turritella agate, orthoceras with garnet

Dinosaur bone, turritella agate, orthoceras with garnet

P.S. Super old time rock n’ roll music!


Ray Troll, the artist who did the fantastic strata/age of rock illustration from previous post, cowrote a song about the geologic eras, have to share it!


Brighter Lights, Thicker Glasses did a song about the Cambrian Explosion and another about the Silurian (the era, not the Doctor Who aliens)-might help you figure out how to pronounce some of the names of famous creatures too!


Okay, and even though the T-Rex bit is outdated, you can’t have a fossil music list without the Symphony of Science.

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Filed under Crafts, Gems, Natural Science

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