Petrified Stone (Fossil Wood)

Petrified Wood is one of my absolute favorite stones to use in aquascaping.

The exotic look bares a close resemblance to vivarium rocks like Dragon Stone and Strata Rock and makes a nice alternative when those stones aren’t available.

Despite the lack of benefits this rock may offer compared to others, it is an inert stone great for all types of vivariums.

This article will serve as a guide to everything you should know before using Fossil wood in an aquarium or terrarium.

Quick Stats:
Traditional Name Petrified Wood
Common Names Fossil Wood, Petrified Stone
Origin Volcanic Deposit, Sedimentary Rock
Habitat Petrified Forest, Volcano Fields
Color White, Black, Tan, Brown, Pink, Green, Blue
Density (g/cm3) 2.58 – 2.91g
Hardness 7
PH Impact Neutral (No Effect)
Elemental Type Sedimentary Rock (Quartz)

What Is Petrified Wood?

Petrified Wood is a sedimentary rock composed of mostly silicate minerals like quartz along with calcite, opal, and pyrite on occasion.

It is commonly referred to as Fossil Wood or Petrified Stone because it is technically a fossilized version of some type of plant material.

The word in itself literally translates to “wood turned to stone” in Latin.

Fossil Wood can virtually take any shape the original plant was and be found all over the world.

Petrified Stone "Fossil Wood" Aquascape Tips

Petrified Wood Facts

Even though this stone looks very much like a portion of an ancient tree, all matter that would typically make up the tree is replaced with sediments of sand and compressed to form the existing stone in the shape of a tree.

Through the process of petrification, the original tree is buried deep enough to decay completely while simultaneously deprived of oxygen.

The shell of that plant material is then filled with mineral-rich groundwater and those minerals harden turning into the sedimentary rock left behind.


The color of Petrified Wood can vary greatly depending on the type of impurities formed within the stone.

For starts, the mineral quartz that makes up the majority of the stone is often clear or white.

Virtually all Fossil Wood will exhibit a combination of many colors due to the many minerals mixed in with quartz.

If the iron oxide is present the colors brown, pink, or red will be found throughout the stone.

Yellow, brown, or orange will indicate a hydrated iron oxide is present within the rock.

Other colors like blue or purple are signs of manganese oxide and black is iron sulfate.

The texture of Fossil Wood will often be non-porous and similar to the organic plant in its shape after.

A closer look will reveal the fine-grained, uniform texture quartz usually has.

Petrified Wood can be tumbled or polished into a perfectly smooth surface.

The density of this rock is generally between 2.58 and 2.91 grams per cubic centimeter.

This would make the rock rather heavy to work within large amounts.

Securely place it in vivariums when using larger sizes and be sure to keep it away from the glass sides of aquariums.


Petrified Wood can only take place underground.

In many cases, it will form within a sedimentary rock only to be revealed when dug up or moved naturally.

Another natural phenomenon that will cause Fossil Wood to form is volcanic activity.

During an eruption, ashes and cooling magma can bury the entire forest.

This will inevitably lead to petrified forests forming in areas around volcanic fields.

Environmental Influence

Being composed of mostly quartz, Petrified Wood typically has no influence on water parameters.

This makes the rock inert and suitable for both hard and soft water vivariums.

Over time, it is possible for minerals to leech during weathering but with a hardness of 7…

It will be a very slow process and should have no negative effects on water hardness or PH.

It is always good to practice doing an alkaline test on any type of rock and if the Fossil Wood does appear to be slightly alkaline, the use of plants and driftwood should be enough of a buffer.

Vivarium Preference

The neutral PH/hardness influence would make Petrified Wood ideal for both saltwater and freshwater aquariums.

Having a hardness of 7 makes this stone durable enough to handle most pets being kept in the enclosure with it.

I would recommend this rock in vivariums like aquariums, ripariums, and paludariums that are either hard water-dependent or softwater planted tanks.

Using these rocks in terrariums works just as well and can either be used as a hardscape or substrate cover.

The unique features Fossil Wood exhibits will add value to any biotype.


Besides the eccentric look, Petrified Wood brings, it is a safe rock considered to be inert and can be used in any type of enclosure.

The possible leaching of metals like iron into an aquarium over slow periods of time can be very beneficial to plants.

The minerals that make up the stone are high on the hardness scale and will prove to last a long time with very little weathering.


Like many stones that contain quartz, Fossil Wood can be rather heavy when used in large amounts.

This can lead to damage to the enclosure or harm to the inhabitants if not securely placed within the tank.

Extremely colorful variations of the rock could potentially have harmful minerals within it as well which could lead to injury to more sensitive fish and invertebrates.

If possible, try to aim for colors that are generally free of green, black, purple, or blue as they tend to contain carbon, cobalt, chrome, or copper.

Buy Petrified Wood

Petrified Wood can be purchased rather easily depending on where you are located. It is generally found all over the world and comes in many varieties.

We were able to find a source that carries it for the intent of vivarium use.

Click the image below to find out more about the current price and other relative info:

Petrified Wood Recommendations

Here are a few more useful tips when working with Petrified Wood for the first time.

Inspect the rocks to see what type of rock has been acquired.

Based on the color as well as the sturdiness of the stone, you should be able to identify the possible minerals compacted into the formation of this rock.

Before placing this stone in any type of vivarium, always soak the stone and do a visual assessment to assure there are no pests or toxic minerals contained within the rock.

As usual, clean the rocks to remove access dust or loose particles from the surface.

Cleaning Petrified Wood

It is always good practice to clean Petrified Wood when buying it from a source.

This will assure all loose sediments are removed as well as potential toxins.

Begin by placing stones in a bucket of cold water.

Scrub and redip each stone thoroughly in the bucket of water.

Rinse and repeat this process until you are able to place stones in a clean bucket of water and observe no noticeable change in color.

No additional chemicals should be used on Fossil Wood to avoid damage or staining.

Breaking Petrified Wood

Keep in mind, Fossil Wood is harder than glass and will be a little hard to break strategically.

Furthermore, if you decide you still need to crush the rock into smaller parts, use a hammer and cover the stone with a towel.

This is great for breaking the stone into lots of tiny pieces of rock…

The downside to this is the potential pile of the undesirably crumbled pebble.

Another way that I much prefer it is with a rock chisel kit.

Chiseling off parts of the rock along the ridges is a more controlled way to break Petrified Wood into desirable shapes.

No matter which way the rock is broken up, make sure to wear safety goggles because parts of the rock will go air born.

Also, reclean rocks as needed once they are broken.

Rocks Similar To Petrified Wood

When designing a new enclosure for the first time, it would be best to stick with one kind of stone to use as a hardscape.

Furthermore, this type of rock can be hard to come by depending on where you are located in the world.

If for any reason, you find Petrified Wood difficult to acquire, or simply want to consider something different…

There are a wide variety of stones to consider.

Here are some other types of stones one might find are worth taking a look at in the place of Fossil Wood:

River Rocks "Riverstone" Hardscape Guide
Limestone "Calcarenite Rock" Hardscape Guide
Sandstone "Quartzarenite Rock" Hardscape Guide


Petrified Wood is an absolutely perfect addition to both aquariums as well as terrariums.

It can be polished, tumbled, broken, or simply used as is.

The fact that it’s inert means it’s safe to use and perfect for beginners.

I would recommend sticking with the brown wood-like colors to avoid any potential dangers later down the line…

But if you decide to use a more colorful piece for your enclosure you should be ok.

Just be sure to keep an eye on the water parameters and the pets sharing the tank.

What are your thoughts about Fossil Wood as a vivarium rock now that you’ve read this entire article?

Frequently Asked Questions

Fossil wood is the term used to describe petrified wood preserved in the fossil record. Petrified wood is the product of a tree or treelike plants that have undergone replacement of its original organic components (such as cellulose) with minerals, mainly sand, silt, and clay. This process can take millions of years and the resulting fossil wood often contains a distinctive pattern of wood grain or wood cell structures making it a unique and valuable treasure found in the natural world.

Yes, fossilized wood is rare. Fossilized wood forms by undergoing a process of mineralization where minerals replace the cells of the original wood. This process usually requires specific environmental conditions such as the presence of sediment or acidic water. Additionally, the fossilized wood must remain intact for millions of years in order for the process of petrification to occur, making the occurrence of fossilized wood rare.

Wood is a type of fossil known as petrified wood, which is created when the organic material of the wood is replaced by minerals. Petrified wood can be found in a variety of colors, such as brown, red, green, yellow, and white.

Fossilized wood is made of bones, petrified wood, and sediment. It is created when a tree dies and is buried in sediment. Over time, mineralrich water seeps through the sediment, replacing the organic parts of the tree with minerals. This process creates fossilized wood.

The rarest color of petrified wood is the goldenhued Chromoxylon, which is composed of quartz, iron oxide, and pyrite.

Fossil wood is wood that has been preserved underground for millions of years. The lack of oxygen and bacteria underground prevents organic decay, resulting in the wood becoming extremely dense. This density is the key factor that makes fossil wood difficult to burn it contains too much carbon for most fires to burn. To burn fossil wood, one must use a special kind of hightemperature fire or expose the wood to coal in order to draw out its moisture.

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