Petrified wood is an example of a fossil formed when tree and other material is buried and preserved from decaying over millions of years. Petrified wood has been preserved in a mineral-rich sediment and water that is free of oxygen that enables its preservation to the point where the wood has largely rotted and been replaced by minerals.
Petrified is a Latin word and effectively refers to how wood and other plant material is turned into stone during the process of petrifaction (or petrification). During petrifaction, the original wood material is almost entirely replaced by silica and other components such as iron and aluminum which gives the petrified wood its color.
Here are 9 questions about petrified wood answered in detail.
What is the meaning of petrified wood?
Petrified wood is an example of a fossilized artifact that has been formed over millions of years. While the original piece was mostly likely a log or other piece of wood or other plant-based substance, over this time the petrifaction process results in around only 10% of the original material remaining. The wood is replaced by silica and natural minerals like iron and magnesium.
The result is something that looks and feels like wood, has no bark, is very heavy and is hard.
How long does it take for wood to petrify?
Petrifaction takes millions of years to occur. When a piece of wood is petrified, it has been quickly buried in deep water rich in minerals and away from oxygen which helps to prevent if from decaying.
The resulting petrified wood is solid and heavy, much more so than many of the woods that exist in fresh green form.
How much does petrified wood weigh?
Petrified wood is solid and heavy
, weighing between 160 lbs and 200 lbs per cubic foot. By comparison, fresh wood from trees is much lighter:
Balsa wood is very light at 7.5 lbs per cubic foot whereas mahogany is 24 lbs – 35 lbs per cubic foot.
The heaviest and hardest wood in the world is purported to be lignum vitae which weights 85 lbs per cubic foot.
Is petrified wood worth anything?
The commercial value of petrified wood is determined by its grade and its form. Petrified wood can be low or high grade depending on a number of features including:
- Its size
- Where it is found
- What it is made from
- The quality of the piece
- Its natural polish if any
- Any natural flaws or cracks
- The level of silicification
- Personal preference
High grade petrified wood has a pleasant color, is relatively free or completely free of fractures and is completely silicified meaning the wood has been replaced by silicate minerals.
Low grade petrified wood is visibly low quality and is often used in cheap jewelry, has flaws, is easily found and may have other unpleasant or plain features.
You can have petrified wood appraised and can start with the International Gem Society to learn more about appraisal options.
What can petrified wood be used for?
Petrified wood can be valuable to collectors as well as to scientists who wish to study the material to learn more about it. Petrified wood can also have commercial applications as it can be used to make tables, jewelry and other items that can be sold.
Higher end petrified wood can be used for lapidary work which refers to the art of stone work. Pieces of petrified wood can used to make large items such as tabletops or smaller items such as clockfaces and smaller jewelry items such as pendants and necklaces.
How can you tell how old petrified wood is?
There are several ways that petrified wood can be dated to determine its age:
Relative Dating
Relative dating is a process of using rocks and other materials around the petrified wood to determine its relative age. It puts the items being studied into chronological order but doesn’t produce an actual age.
Biostratigraphy
This process uses relative ages of rock and surrounding materials to determine the age of petrified wood by comparing it to other fossilized organisms in the same layer.
Radiometric Dating
Also known as radioactive dating, it is typically used to date rocks and other materials by using known decay rates to determine the age of petrified wood using comparative methods.
Is petrified wood rare?
Petrified wood is not rare and is widely available around the world and is typically found in volcanic areas and among sedimentary rock and in forests.
Research has shown that while true petrified wood takes millions of years to form, in the right conditions silicified wood can occur in hundreds of years and as little as 10 years in hot springs.
What popular tourist areas have petrified wood to see?
In the United States, some of the most common locations for petrified wood include:
| Name | Location | Details |
| Petrified Forest National Park | Petrified Forest, Arizona | Over 13,000 years old. Has trails to walk and hike on and a museum to visit among other attractions. |
| Calistoga Petrified Forest | Sonoma County, California | A forest with numerous other forests, vineyards, wineries and other attractions nearby. Is repute to have the largest petrified trees in the world including coniferous trees, tree ferns, and some gingkoes. |
| Gallatin Petrified Forest | Tom Miner Basin, Montana | See fossilized upright trees including sycamores, oaks, maples, dogwoods, magnolias, buckthorn, laurels, chestnuts, and redwood trees that date back over 50 million years in age. |
| Escalante Petrified Forest State Park | Wide Hollow Reservoir, Utah | Dating back over 150 million years, this park features plants and marine fossils, petrified wood and fossilized dinosaur bones. You can also rent a canoe, kayak or paddleboard on the reservoir or hike through the nature trails. |
| Wolverine Petrified Wood Area | Boulder, Utah | Officially known as Wolverine Petrified Wood Natural Environmental Area. Located in southern Utah, the park is over 225 million years old and is over 3,800 acres in size. The largest logs and petrified wood are found near the Wolverine Creek area. |
| Zion National Park Petrified Forest | Springdale, Utah | Part of the Zion National Park, the petrified forest is part of a much larger attraction. Given that it’s part of a very well known park, be sure to visit the other attractions such as the desert swamp, springs and waterfalls, Emerald Pools and hanging gardens. |
| Ginkgo Petrified Forest State Park | Kittitas, Washington | It’s part of a 7,124-acre park with camping facilities and 27,000 freshwater shoreline located on Wanapum Lake. The park also has day-use picnic areas and has over 50 types of petrified wood to view including ginkgo, sweetgum, redwood, Douglas fir, maple, walnut, spruce and elm among many others. |
| Yellowstone Petrified Forest | Wyoming, Montana and Idaho | Part of the world famous Yellowstone National Park, the petrified trees are over 50 million years old and are found among volcanic rock and debris that are responsible for the phenomenon. The park is also known for housing both body fossils of various organisms as well as trace fossils of footprints and other artifacts. The park is largely location in Wyoming but stretches into Montana and Idaho with 5 total entrances available. |
Is it legal to take petrified wood home as a souvenir?
While fossilized rock is often very abundant, some areas don’t allow the collection of petrified wood for personal use particularly on private property.
However like any artifact, if everyone who came across petrified wood on private property or in a forest took some of it with them, it would negatively affect the future viability and enjoyment of others if it is taken in large quantities. Petrified wood is a fossil and is thus protected by US laws especially when located on State-owned land.
Keep learning about wood by checking out my article called 11 Amazing Facts About Wood (Questions Answered).