Petrified Wood
Silicified Wood (Quartz var. Chalcedony/Opal replacing organic material) · Mineral Specimen / Organic Gemstone (Pseudomorph)
Crystal System
Trigonal/Amorphous (microcrystalline Quartz or Opal); maintains the fibrous or massive habit of the original wood structure.
Mineral Group
Silicates (Tectosilicate group)
Chemical Formula
SiO2 (Silicon Dioxide) with traces of Iron (Fe), Manganese (Mn), and Carbon (C)
Formation Process
Permineralization (a type of fossilization) where organic material is replaced by silica-rich water in anaerobic conditions, typically under volcanic ash or sedimentary layers.
About This Crystal
An opaque, woody-textured specimen showing distinct longitudinal graining and ring layers. Colors range from tan and cream to brownish-red, with a dull to waxy luster.
Physical Characteristics
Color: Brown, tan, and beige; Streak: White; Cleavage: None; Fracture: Conchoidal or splintery; Specific Gravity: 2.6–2.9; Non-fluorescent usually, but some may show weak green/yellow.
Optical Properties
Refractive Index: 1.544–1.553 (Quartz) or 1.45 (Opal); Opaque to translucent; No pleochroism; generally isotropic or aggregate reaction under polariscope.
Hardness & Durability
Origin Region
Arizona (Petrified Forest National Park), Madagascar, Indonesia, and Argentina; found in ancient fluvial or volcanic environments.
Hardness & Durability
Mohs Hardness: 6.5 to 7.0; Toughness: High (durable); Stable for jewelry but can be brittle if high in opal content.
Care & Maintenance
Wash with warm soapy water; avoid harsh chemicals and ultrasonic cleaners if the specimen is porous or dyed. Store away from harder gems like Topaz or Sapphire.
Rarity & Value
Common globally, but high-quality colorful specimens (Rainbow wood) are collectible. Price ranges from $1 for small rough pieces to thousands for polished slabs.
Special Characteristics
Pseudomorphism: The mineral has perfectly preserved the cellular structure and external shape of the original biological wood fibers.
Lore & History
Historically used as amulets by many cultures; symbol of longevity and ancient wisdom. Metaphysically associated with grounding and ancestral healing.