sedimentary
Petrified Wood
Silicified Wood (SiO2)
Hardness: 6.5-7 (Mohs scale), Color: Brown, gray, black, with yellow or reddish highlights, Luster: Vitreous to dull, Crystal structure: Microcrystalline quartz, Cleavage: None, Specific gravity: 2.6-2.9
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (Mohs scale), Color: Brown, gray, black, with yellow or reddish highlights, Luster: Vitreous to dull, Crystal structure: Microcrystalline quartz, Cleavage: None, Specific gravity: 2.6-2.9
Formation & geological history
Formed via permineralization where organic wood materials are replaced by minerals (usually silica) over millions of years in anaerobic conditions, often under layers of volcanic ash or sedimentary silt.
Uses & applications
Used for lapidary work, jewelry (cabochons), interior decor (tabletops, bookends), and as teaching specimens in paleontology.
Geological facts
Petrified wood is a fossil where the original cellulose structure is entirely replaced by minerals while retaining the anatomical details of the tree's bark and rings.
Field identification & locations
Identify by looking for preserved wood grain, growth rings, or bark textures in a heavy, stony material. Commonly found in Arizona (USA), Madagascar, and Indonesia.
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