fossil
Petrified Wood
Silicified Wood (SiO2 permineralization)
Hardness: 6.5-7 Mohs; Color: Brown, red, tan, orange; Luster: Vitreous to dull; Crystal structure: Trigonal (cryptocrystalline quartz); Specific gravity: 2.6-2.9
- Hardness
- 6
- Color
- Brown, red, tan, orange
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6.5-7 Mohs; Color: Brown, red, tan, orange; Luster: Vitreous to dull; Crystal structure: Trigonal (cryptocrystalline quartz); Specific gravity: 2.6-2.9
Formation & geological history
Formed through permineralization over millions of years (often Jurassic to Triassic), where organic material is replaced by silica/chalcedony in anaerobic conditions under sediment.
Uses & applications
Used for jewelry making, lapidary arts, decorative furniture, and as a popular collector's specimen.
Geological facts
The colors are provided by trace elements: iron yields reds and yellows, mentre manganese can produce pinks or blacks. The wood structure is often so well preserved that tree rings and cellular detail can be viewed under a microscope.
Field identification & locations
Identify by looking for wood-like textures, grain patterns, or bark-like exteriors on heavy, rock-like material. Common in areas like Arizona (Petrified Forest NP), Oregon, and Madagascar.
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