sedimentary
Petrified Wood / Jasper Chert
Silicified Wood / Microcrystalline Quartz (SiO2)
Hardness: 6.5 - 7 on Mohs scale. Color: reddish-brown, tan, cream, and yellow hues with fine banding or cellular structure. Luster: waxy to vitreous. Cleavage: none (conchoidal fracture). Specific Gravity: 2.6 - 2.65.
- Hardness
- 6
- Luster
- waxy to vitreous
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Physical properties
Hardness: 6.5 - 7 on Mohs scale. Color: reddish-brown, tan, cream, and yellow hues with fine banding or cellular structure. Luster: waxy to vitreous. Cleavage: none (conchoidal fracture). Specific Gravity: 2.6 - 2.65.
Formation & geological history
Formed through permineralization, where organic wood material was buried rapidly under sediment and replaced molecule by molecule with silica-rich groundwater, often during the Triassic to Tertiary periods.
Uses & applications
Used primarily for lapidary work, jewelry, cabochons, decorative ornaments, and as educational or geological collection specimens.
Geological facts
Petrified wood can retain cellular wood structures down to the microscopic level, allowing paleobotanists to identify species of prehistoric trees that lived millions of years ago.
Field identification & locations
Identified in the field by its blocky or fibrous grain texture reminiscent of wood combined with a high hardness (scratches steel). Commonly found in sedimentary basins, ancient riverbeds, and gravel deposits worldwide (e.g., Arizona Petrified Forest).
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