Is Wood a Mineral? (and What About Petrified Wood?)

No, wood is not a mineral, because it is an organic (meaning living or made up of living material), varies in chemical composition, and its structure is disorderly.

To understand a little more about why wood is not a mineral, and also to understand more easily why other materials are or are not minerals, read on to learn about what makes a mineral a mineral, as well as the more extended analysis as to why wood is not a mineral.

First, What Makes Something a Mineral?

To be considered a mineral, a substance must meet five requirements:

  • The material must form on its own without the assistance or interference of humans
  • The material is a solid (and not a liquid or a gas)
  • The material is inorganic, though it can be formed from an organic process.
  • The material has a consistent chemical composition
  • The atoms in the material are arranged in an consistently orderly manner.

If it fails to meet any one of these (or more than one) then it cannot be called a mineral.

Does Wood Meet Any of the Requirements?

Yes, wood does meet some of the requirements. But as we said, not all. And for that reason, it does not qualify.

Wood is a material that forms on its own without the assistance or interferences of humans. It grows! Humans definitely plant trees, but trees do not rely upon humans to make them.

Wood is a solid, and not a liquid or gas.

Wood is considered an “organic” material. It is a living material.

Wood also varies in chemical composition. The chemical composition of wood can not be defined for a given tree species or even a given tree.

It will vary with the part of the tree, such as a root versus a branch, the geographic location, climate, and the soil conditions. The variation is such that chemical composition cannot even be used to identify individual tree species. (source)

Finally, the structure of wood is not orderly and consistent (not crystalline).

The Results Are In: Is Wood a Mineral?

Because wood does not meet the five requirements, it is not a mineral.

Is Petrified Wood a Mineral?

This is a good question, isn’t it! To answer it, let’s first talk about what petrified wood is.

The name “petrified wood” is a bit confusing. At this point (if the wood is petrified), it isn’t really wood any more. Petrified wood is wood that has completely changed into something else.

It forms when the wood is buried completely, so completely that it does not decay because the dirt/material prevents oxygen and organisms from breaking it down.

Over time, as water rich with dissolved minerals seeps into the wood, all of the organic materials are replaced with silica, calcite, pyrite, opal, or other inorganic materials.

This happens over time, and in stages. The materials in the wood that are the weakest and easiest to break down are replaced first.

As the years pass and pass, the more resilient materials are broken down and replaced. This is why you can still see the rings in the wood.

While you might still be able to see the features of the wood (like rings, the stump, what looks like bark), the wood is no longer wood in any sense of the word.

Petrified Wood: Step by Step Through the Minerals Test

Let’s walk through the same test that we put wood through above.

First, petrified wood is something that forms without the assistance of humans.

Second, petrified wood is a solid, and is not a liquid or a gas.

Third, petrified wood is not composed of organic material. While it may have once been organic material, those materials decayed over time and were actually replaced by the minerals that is is now made of. Those minerals are inorganic.

Fourth, the chemical composition is not consistent throughout the material. Well, usually. In general, petrified wood is composed of many different kinds of minerals. That being said, it could be found with perhaps only one mineral (like opal). But if that were the case, we’d call the material an opal rather than petrified wood.

Fifth, the structure of the minerals in the material are orderly and consistent.

Is petrified wood a mineral? No, it is not.

People will say that because petrified wood is beautiful, and treated like other minerals (collected, polished, made into jewelry), that it is, itself, a mineral.

In our opinion, based upon the five characteristics required to be called a mineral, that the material is not a mineral.

Instead, it is composed of minerals.

How Long Does It Take To Make Petrified Wood?

It takes millions of year for petrified wood to form.

Can You Burn Petrified Wood?

Not the way you’d expect. Since all of the “wood” elements in the material have been replaced with minerals, it won’t burn like wood. It will be like throwing a rock into the fire.

Petrified wood is usually very hard, on a 7 to 8 on the Mohs scale of hardness. You’d need a diamond-tipped wet saw to cut it.

In fact…this guy made a fireplace out of petrified wood.

That being said, it is possible that some of the minerals that replaced the organic elements in the material will burn if the fire is hot enough.

Interested in learning more about rocks and minerals? Or whether other materials like charcoal or oyster shells are minerals?

Check out our Knowledge Vault for our latest posts as we dig deeper and learn more about the Earth.