Petrified Wood

Physical Properties

Hardness: 6.5-7 (Mohs scale); Color: Variegated brown, red, grey, and white; Luster: Vitreous to dull; Crystal Structure: Cryptocrystalline; Cleavage: None; Specific Gravity: 2.58-2.91

Formation & Geological History

Formed through permineralization where organic wood materials are replaced with silica (chalcedony or opal) from groundwater while buried under sediment or volcanic ash. This specimen likely dates from the Mesozoic or Cenozoic eras.

Uses & Applications

Used for decorative ornaments, jewelry (cabochons), furniture tops, and as a popular geological collectible.

Geological Facts

The colors are caused by trace elements: iron oxide produces reds and yellows, while manganese produces pinks and oranges. Some of the most famous deposits are in Petrified Forest National Park in Arizona.

Field Identification & Locations

Identify in the field by looking for bark textures, growth rings, or cellular structures preserved in stone. Commonly found in sedimentary basins or areas with historical volcanic activity.

Identified on: 5/10/2026

Mode: Standard