sedimentary
Petrified Wood
Silicified Wood (SiO2)
Hardness of 6.5 to 7 on the Mohs scale, colors range from gray and brown to red and yellow due to mineral impurities, vitreous to waxy luster, microcrystalline quartz structure with no cleavage, and a specific gravity around 2.65.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, colors range from gray and brown to red and yellow due to mineral impurities, vitreous to waxy luster, microcrystalline quartz structure with no cleavage, and a specific gravity around 2.65.
Formation & geological history
Formed when organic plant material is buried in an oxygen-depleted environment under sediment and progressively replaced by minerals, primarily silica, over millions of years (often dating from the Triassic period or younger).
Uses & applications
Used primarily in lapidary arts, decorative items, bookends, jewelry, and prized by collectors and museums.
Geological facts
Petrified wood preserves the original cellular structure of the ancient trees down to microscopic details, turning organic tissue completely into stone while maintaining the wood grain appearance.
Field identification & locations
Can be identified in the field by its distinct wood-like grain and texture combined with a stone-like weight and hardness that can scratch glass. Commonly found in areas with ancient forests and volcanic activity, such as the Petrified Forest National Park in Arizona.
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