No, petrified wood does not float in water.
The petrification process actually replaces all of the organic cells and matter with minerals.
The minerals/rock that replace the organic wood cells are denser than water.
As a result, a true piece of petrified wood (no matter how old or gnarly it looks), will not float in water.
Want to learn more about the petrification process?
We’ll explain below.
Why Does Petrified Wood Float? (Or Not?)
Petrified wood is created under only very specific circumstances.
Millions of years ago (not hundreds, or even thousands of years), a piece of wood (log, stump, branch) was covered up in a way that prevented air and organisms from getting to the cells of the wood.
Maybe it was covered up in a landslide.
Maybe the tree fell into a bog.
Maybe a volcano erupted and covered the wood completely with ash.
Without the air and the organisms, the cells of the wood didn’t decay like that would have if the organic cells had been exposed.
Over time (millions of years), groundwater carrying traces of minerals (like silicon dioxide, calcite, iron oxides, pyrite, metals, and more) seeped into and through the wood.
The water passed through, disrupting the organic material, moving it, and replaced those cells with the mineral deposits.
This might be hard to understand, as this process happens so, so, so very slowly, and at a level so small in the wood that it is hard to even conceptualize.
Just imagine teeny tiny bits of the wood leaving the material along with the water slowly, over time, leaving the minerals behind in their place.
This happens so gradually that the structure of the wood is mimicked by the minerals.
The colors of the petrified wood will vary, depending upon what mineral is being carried through by the water.
But in any case, the wood, which is less dense, is entirely replaced.
There is no wood left.
This is why petrified wood does not burn.
This is also why letting petrified wood sit in water doesn’t do much to it, aside from making it more likely to crack or break under stress.
Could Petrified Wood Float?
Any piece of material that is truly petrified wood will not float in water.
It doesn’t matter how large or small the piece is.
Extremely old/hard wood, maybe even worn so smooth that it looks like a stone, cannot be petrified wood if it floats in water.
That being said, petrified wood could float, if it was placed into a liquid that was somehow more dense than the petrified wood.
But absent that extremely rare circumstances, you won’t see petrified wood floating.
This is why putting a piece of suspected petrified wood can be a great way to help you conclude whether you have petrified wood or not.
Other Ways To Help Identify A Piece Of Petrified Wood
As noted, a float test is a great way to help figure out whether a stone with thin lines that resembles tree rings is petrified wood.
But you can also help identify (or at least rule out) some pieces with a little bit of knowledge about petrified wood.
As noted above, petrified wood is formed when minerals replace the organic structures.
These minerals are generally extremely hard, usually in the range of 5-7 on the Moh’s scale.
This means that petrified wood is not easily scratched.
If you can drag your fingernail over a piece of suspected petrified wood and your nail leaves a nail track/mark, that’s not petrified wood.
It’s too soft.
You can’t scratch quartz (which is also made up of silicon dioxide) with your fingernail.
The same is true of a copper penny, or maybe even a shard of glass.
Why Identifying Petrified Wood Is Challenging
Petrified wood is most easily identified when it is in a large piece, near intact.
This means you can see the bark on the outer edges of the piece, and also observe the circular annual rings.
When the petrified wood has been broken apart into pieces (or purpose or by the elements), petrified wood often just looks like the minerals that make it.
Like an agate.
Or a jasper.
Or a piece of colored quartz, like citrine or strawberry quartz.
If the piece is too small, you won’t be able to observe the rings or the bark.
And you’ll never know that your beautiful agate was formed over millions of years as part of a tree.
Did you know that your petrified wood could be radioactive?
As it turns out, the answer to that question is interesting and not nearly as scary as I had imagined.
If you are still interested in learning more about rocks and minerals, check out our blog for our latest informational articles about materials found around the world.