What are Organic Gems? 

Although most gemstones are mineral materials, a number of organic materials are also considered to be gemstones. The most common of these are pearl, bone, amber, coral, and ivory. These are materials, produced by organisms, that have been cut into gems and other ornamental objects. 

There are also organic materials that have been mineralized (replaced and infilled by chalcedony, opal, calcite, aragonite, pyrite or other mineral material). Although the material itself is not organic, it does preserve an organic structure. Examples include petrified wood, fossil coral, dinosaur bone and other fossilized organisms or parts of organisms. 

On this page we present a photo gallery of organic gemstones. The photos in the left column (below) are organic materials. The photos in the right column (not including the top collage) are fossilized organisms.

Organic Materials

Pearls

Yes, pearls are considered to be "gemstones." They are produced by mollusks and other shellfish. People have used them as gems for thousands of years. The pearls in this photo are cultured freshwater pearls produced in Tennessee.

 

Amber

Amber is a fossilized resin that was secreted by ancient plants. It usually has a yellowish to orangish brown color but can be white, greenish, bluish or even black. It is easily cut and polished into bright, light-weight gems.

 

Coral

Coral is a colonial organism that lives in warm, shallow marine waters and often develops reefs. It is a hard calcium carbonate material that can be cut or carved and polished into beautiful gems. The coral is usually white, cream, or pink in color. Rarely it is bright red, the most desired color. These specimens of pink coral are from Taiwan .

 

Jet

Jet is a variety of bituminous coal with a uniform texture that can be cut and polished into attractive gems. It was popular in Victorian England and used in mourning jewelry. One of the most famous jet-producing localities is near the community of Whitby on the eastern coast of England. Jet, as a form of coal, has a very low specific gravity. That makes a long strand of jet beads much lighter in weight than a similar-size strand of any other gem material except amber. Pins, pendants, and earrings made from jet are also much lighter than those made out of other materials and can be worn more comfortably. 

 

Mother of Pearl

Mother of pearl, also known as "MOP," is the thin inner nacreous layer of a mollusk shell. It can have a base color of white, cream, or gray with a beautiful iridescent play-of-color. Mother of pearl has been used to produce jewelry and buttons. It has been used for fancy inlay work on musical instruments and furniture. It was much more commonly used before plastic manufacturing became common. 

 

Ivory

Ivory is a white- to cream-colored material that is from the tusks of elephants; the teeth of other large mammals such as hippopotamus, walrus and wild boar; or the fossilized tusks of mammoths. It is widely carved and inscribed for use as ornamental objects and less often as gems. Most countries of the world now ban or heavily regulate the sale and import of elephant ivory. This ivory bracelet is from the Tropenmuseum Collection and their photo is used here under a Creative Commons License. 

 

Ammolite

Ammolite is a trade name used for iridescent ammonite shell material. It produces a bright flash of color that rivals fine opal and labradorite. All of the world's production comes from a small area in Alberta, Canada.

Fossilized Organisms 

Petrified Wood

Petrified wood is a fossil that forms when woody material is buried, then dissolved materials in ground water precipitate to replace and infill the wood structure with silica, opal or other mineral material.

 

Petrified Palm

Petrified palm, also known as "petrified palm wood," is a material commonly found in the Oligocene-age sediments of the United States Gulf Coast. It is not actually a wood, instead it is fossilized parenchyma, the fibrous material that composes a palm tree. It is described in detail in our article on Louisiana gems.

 

Fossil Coral

Coral (left) and bryozoans (right) are organisms that live in warm, shallow marine waters. They are often fossilized by infilling and replacement with quartz or calcite. These materials can be polished into attractive gems. 

 

Dinosaur Bone

Dinosaur bone is often petrified (fossilized by being infilled and replaced by quartz and other minerals). The quartz can be very colorful. When the petrification is thorough, the material can often be cut and polished into attractive gems. 

 

Mary Ellen Jasper

Mary Ellen Jasper is a rock found in Minnesota that consists of red jasper and silver hematite. The jasper is a fossil stromatolite, a layered structure built up by sediment-trapping algae. The algae that produced the stromatolite structures in Mary Ellen lived on Earth about two billion years ago - long before land plants.

 

Sand Dollar

The sand dollars found on the beach today are from an ancient group of animals that has lived in the oceans for millions of years. Their bodies are often agatized by nature and then found by people who polish them into gems. This sand dollar is an agatized specimen from Mexico.

 

Turritella Agate  

"Turritella Agate" is the name given to a brownish gem material that contains spectacular fossil snail shells entombed in a semitransparent agate. Although millions of people have called this material "Turritella" for several decades, the name is actually incorrect. It was mistakenly named after a genus of fossil snails that are very similar to the shells in the agate. The proper name of the snails is "Elimia tenera," a member of the Pleuroceridae family. Perhaps a more accurate (although less elegant) name for the material would be "Elimia Agate." 

About 50 million years ago, the spiral-shaped shells accumulated in the sediments of a shallow inland sea in an area that we now know as the state of Wyoming. A few lenses of snail-bearing sediment, in what is today known as the Green River Formation, were then agatized by the deposition of fine-grained silica (chalcedony - also known as agate) into the cavities of the shells and the voids between them. If the sediment was completely agatized, it has potential lapidary (gem cutting) potential. To learn more about the Turritella - Elimia naming error visit the Museum of the Earth website, which is authored by the Paleontological Research Institution - people who know what they are talking about when it comes to fossils.

Crinoidal Limestone

Crinoids are organisms that once lived on the ocean floor. They looked like a stemmed plant but were actually an invertebrate animal. Their fossils can be found in limestone and dolomite that can often be cut and polished into interesting gems. This cabochon is about 39 millimeters square and was cut from material found in China.