fossil
Petrified Wood Agate
Silicified Wood (primarily SiO2)
Hardness: 6.5-7 Mohs; Color: Tan, brown, white, and translucent grey; Luster: Vitreous to waxy; Structure: Microcrystalline/cryptocrystalline quartz; Cleavage: None (conchoidal fracture).
- Hardness
- 6
- Color
- Tan, brown, white, and translucent grey
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 Mohs; Color: Tan, brown, white, and translucent grey; Luster: Vitreous to waxy; Structure: Microcrystalline/cryptocrystalline quartz; Cleavage: None (conchoidal fracture).
Formation & geological history
Formed during the permineralization process where organic wood cells are replaced by silica-rich groundwater over millions of years, often in volcanic ash beds or sedimentary river deposits.
Uses & applications
Used for decorative lapidary work, jewelry, bookends, coffee table tops, and as a popular collectible for mineral enthusiasts.
Geological facts
This specimen shows a mix of massive agate and crystal growth, likely from a hollow log or 'pocket' where quartz crystals had space to grow inward towards a cavity.
Field identification & locations
Identify by the presence of wood-like grain patterns or bark textures on the exterior, coupled with a stony, heavy weight and quartz-like hardness. Common in regions like Arizona, Oregon, and Madagascar.
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