Petrified Dinosaur Bone (Gembone)

Physical Properties

Hardness: 6.5-7 (Mohs scale), Color: Red, brown, and gray hues, Luster: Vitreous to waxy after polishing, Structure: Preservation of trabecular (spongy) bone cells replaced by silica/quartz, Specific Gravity: 2.6-2.7

Formation & Geological History

Formed during the Mesozoic Era (Jurassic or Cretaceous periods) through the process of permineralization. Mineral-rich groundwater deposited silica into the pores of decaying bone, eventually replacing the organic material with chalcedony or agate.

Uses & Applications

Primarily used for lapidary work, jewelry making (cabochons), and as a collector's specimen due to its unique cell patterns and historical significance.

Geological Facts

Cells in gembone are often large enough to be seen with the naked eye. In 'gembone' quality specimens, the distinct cellular structure of the dinosaur bone is perfectly preserved in colorful agate.

Field Identification & Locations

Identify by looking for characteristic 'honeycomb' or cellular structure on the surface. Commonly found in the Morrison Formation of the Western USA (Utah, Colorado, Wyoming). Collectors look for vibrant colors and distinct cell preservation.

Identified on: 5/3/2026

Mode: Standard