Agatized Dinosaur Bone

Agatized dinosaur bone is a fossilized dinosaur bone that has been replaced by silica minerals, typically microcrystalline quartz crystals, through a process called permineralization. This results in a colorful, glassy material which can exhibit intricate patterns, and unlike the usual stony appearance of fossilized bones.

Due to the specific conditions required for their formation, agatized dinosaur bones, also known as gembones or dinogems, are much rarer than regular fossils. Agatized dinosaur bones can exhibit a wide range of colors depending on the inclusions. Common colors include brown, yellow, red, orange, blue, and green.

Agatized dinosaur bone is found in many parts of the world, but some of the most famous deposits are in the Morrison Formation of Utah, Wyoming, and Colorado.

Agatized Dinosaur Bone. Credit: Sean Eckel

How is Agatized Dinosaur Bone Formed?

Agatized dinosaur bone forms through a fascinating process involving specific conditions and a mineral called silica. Here's a breakdown of the steps:

Burial: After a dinosaur dies, its bones need to be buried quickly to avoid getting scavenged or weathered away. This rapid burial protects the bones from the elements and creates the right environment for fossilization.

Permineralization: Groundwater rich in silica (silicon dioxide) seeps into the buried bones. This silica-rich water permeates the bone, filling in the spaces within and between the original bone cells.

Dissolution and Replacement: Over time, the original bone material (usually calcium phosphate) gradually dissolves and is replaced by the silica minerals from the groundwater.

Crystallization: As the silica-rich water continues to flow through the bone, the dissolved silica starts to solidify and crystallize. These crystals, typically microcrystalline quartz, eventually form a cast of the original bone structure.

Color and Patterns: Depending on the minerals present in the groundwater besides silica, the agatized bone can develop beautiful colors and intricate patterns. Iron oxides, for example, can contribute to red, orange, and yellow hues.

Preservation: The silica minerals are much harder and more resistant to weathering compared to the original bone material. This process essentially petrifies the bone, preserving its form for millions of years.

Agatized Dinosaur Bone

Agatized Dinosaur Bone Properties

What do Agatized Dinosaur Bones Look Like?

Agatized dinosaur bones come in various shapes and sizes, depending on the original bone fragment they represent. They can be small fragments or even large sections of bone, like vertebrae or limb bones. The agate replacing the bone can display a wide variety of colors, including browns, reds, yellows, oranges, blues, and greens. When polished, these bones reveal a high luster and intricate details of the bone's internal structure.

Visual properties

Color: Unlike the usual brown or gray of regular fossilized bones, Agatized dinosaur bone comes in a wide variety of colors, including browns, reds, yellows, oranges, blues, greens, and purples. These colors are due to the presence of various minerals within the agate or chalcedony that replaced the bone. Often, these colors form beautiful patterns and swirls throughout the stone.
Texture: The silica minerals replace the original bone material, resulting in a glassy or polished appearance. They can be smooth or have a slightly rough texture depending on the crystallization patterns.
Luster: Agatized dinosaur bone has a vitreous or glassy luster.
Patterns: The flow of silica-rich groundwater through the bone can sometimes create intricate patterns within the agate. These patterns can be bands, swirls, or even resemble fossilized bone structures.
Cellular Structure: In rare cases, the agatization process can preserve the original cellular structure of the dinosaur bone. This allows scientists to study the bone's microscopic details and gain insights into the dinosaur's biology.

Polished gem Bone
Photo: Jessa and Mark Anderson

Physical Properties

Hardness: Agatized dinosaur bone is quite hard, with a Mohs hardness of 6 to 7. This makes it durable and suitable for use in jewelry and other decorative items.
Fracture: Agatized dinosaur bone can have a conchoidal or uneven fracture.

Metaphysical Properties

In metaphysical circles, agatized dinosaur bone is believed to possess a number of properties. It is thought to be a grounding stone that connects one to the earth's energy. It is also believed to promote strength, courage, and perseverance. These beliefs are not scientifically validated, but they add to the lore and appeal of this unique material.

This photo shows both rough and cut agatized dinosaur bone.
Photo: Darwin Dillon

Where are Agatized Dinosaur Bone Found?

Agatized dinosaur bones are found in locations where there were once rich deposits of silica minerals millions of years ago, during the fossilization process.

Colorado: The Morrison Formation, which stretches across Colorado, Utah, Wyoming, and New Mexico, is a famous source of agatized dinosaur bones. Dinosaur National Monument in Colorado is a particularly noteworthy location for these fossils.

Utah: The Dinosaur National Monument also extends into Utah, and other areas within the state, like the Kaiparowits Formation, have also yielded agatized dinosaur bone discoveries.

While the United States has some of the most concentrated deposits, agatized dinosaur bones have also been found in other parts of the world, including:

Argentina: The Patagonia region of Argentina has yielded some finds of agatized dinosaur bones.
Brazil: The dinosaur beds of the Paraná Basin in Brazil have also produced a small number of agatized dinosaur bone specimens.
Morocco: Morocco, particularly the regions around the Atlas Mountains, has some deposits containing agatized dinosaur bones.

Agatized dinosaur bone is a valuable material for collectors and can be used to make jewelry, cabochons, and other decorative items. It is also of interest to paleontologists because it can provide information about the dinosaurs' bone structure and even their health.

Agatized Dinosaur Bone cabochon.
Photo: Mark Anderson

Agatized Dinosaur Bone jewelry

Agatized Dinosaur Bone FAQ

How Old is it?

Agatized dinosaur bone can date back to the Jurassic period, around 150 million years ago.

Is it Rare?

Yes, agatized dinosaur bone is a relatively rare gemstone material. The specific conditions required for its formation make it less common than other types of fossils.