Petrified Wood
Silicified Wood (Quartz var. Chalcedony / Jasper) · Mineral Specimen and Decorative Stone
Crystal System
Trigonal (microcrystalline/cryptocrystalline quartz aggregate)
Mineral Group
Silicates - Tectosilicates
Chemical Formula
SiO2 (Silicon Dioxide) with varying trace elements such as iron, carbon, and manganese
Formation Process
Permineralization/Sedimentary-groundwater replacement where organic wood material is buried under sediment in anoxic conditions and gradually replaced by silica-rich water over millions of years
About This Crystal
This hand-held specimen exhibits distinct preservation of original wood grain and bark texture on one side, transitioning into smooth, bluish-gray and brownish chalcedony or agate on the other. It is opaque in the woody areas and translucent to semi-translucent in the silicified portions, featuring a waxy to vitreous luster.
Physical Characteristics
Colors range from dark brown and black in the bark structure to soft gray, blue-gray, and tan in the chalcedony areas. Streak is white. Cleavage is none, fracture is distinctly conchoidal in the quartz areas and splintery along wood grains. Specific gravity ranges from 2.5 to 2.8. Tenacity is brittle.
Optical Properties
Displays aggregate double refraction (birefringence) under a polarizing microscope due to its microcrystalline quartz structure. Generally non-pleochroic and exhibits no chatoyancy, but polished surfaces display a vitreous to waxy sheen.
Hardness & Durability
Origin Region
Found globally; notable deposits include the Petrified Forest National Park in Arizona, USA, Madagascar, Argentina, and Washington State
Hardness & Durability
Mohs hardness of 6.5 to 7, making it quite durable and suitable for various ornamental and lapidary uses, comparable to quartz.
Care & Maintenance
Easily cleaned with warm soapy water and a soft brush. Avoid harsh chemical cleaners and prolonged exposure to direct sunlight if dyes were used, though natural specimens are generally stable.
Rarity & Value
Common to Uncommon depending on the quality of preservation, color, and size. High-end polished display pieces with vibrant replacement minerals can command moderate to high collector prices.
Special Characteristics
Remarkable preservation of cellular plant structures, sometimes completely replaced by agate, jasper, or opal, preserving the macroscopic features of ancient forests.
Lore & History
Often used in crystal healing as a grounding stone linked to the root chakra, symbolizing patience, ancestral connection, and stability. Historically valued by collectors and lapidaries for its dual nature of wood and stone.