Do you have a fire pit and you are looking to get a useful and decorative medium? Then consider using lava rocks, also known as Basalt. Lava rocks are igneous stones formed when lava erupts from a volcano and cools on the surface. They have various mineral and chemical components that make them a functional yet aesthetically pleasing fire pit medium.
- Mineral Components of Lava Rocks
- Chemical Components
- Benefits of Using Lava Rocks in a Fire Pit
- Burning Wood Over Lava Rocks
- Different Types
- Prices and Cost Effectiveness
- How Much Do You Need For Your Fire Pit
- Assembling The Fire Pit With Lava Rocks – What To Do
- Potential Dangers
- Odors and Smells to Look Out For
- Where To Buy Lava Rocks
Mineral Components of Lava Rocks
Volcanic lava contains various minerals, when the lava dries to form rocks, the minerals form an integral part of the structure.
Common minerals found include:
- Amphibole
- Olivine
- Quartz
- Plagioclase feldspar
- Amphibole
- Magnetite
- Biotite mica
- Pyroxene
- Hornblende

Chemical Components
The chemical components of lava rocks make them durable and hard to withstand high heat. There are various main components and others found in minute quantities, they include:
- Iron
- Calcium
- Magnesium
Benefits of Using Lava Rocks in a Fire Pit
Protective Porous Surface
Lava rocks are porous, which means that they have small air spaces in them. When they are used in a fire pit, they provide a porous barrier that protects the inner components. These air spaces are created by gas bubbles within the lava. The porous nature of the rocks allows water and air to pass through, protecting your fire pit components from surface heat at the same time keeping the rocks dry.
Protects The Burner From Exposure
It is recommended to us at least 3-4 inches of lava rock as your fire pit medium. This will insulate and protect the burner from getting exposed to weather elements. The lava rock provides waterproofing for those critical burner components, protecting them from corrosion and severe weather.
Air spaces provide good insulation, protecting the burner from surface heat when you are actively using the fire pit. This increases its lifespan and minimizes maintenance costs.
Even Flame And Heat Distribution
Lava rocks have an incredible ability to hold heat, this makes the heat distribution even over their surface. When using gas, the small air spaces within the rocks distribute the gas over the surface, this makes the flame evenly distributed over the fire pit. Using lava rocks will eliminate the ever-annoying cold spots making sure there’s an even distribution of flame and heat.
Cheap
For the incredible work and functionality that lava rocks provide, they are cheap and easy to source. Prices vary from $2-$4/lb depending on the type. You can get them at your nearest convenience store or online store.
Durable and Sturdy
Lava rocks are quite durable. Their chemical components make them have high melting points to withstand the high heat without melting or turning to ash. They can be used over and over for a long time without needing any replacement. Washing the rocks regularly will also increase their lifespan. Another great benefit is that they don’t deform or change color because of use thus the natural aesthetic remains intact.
Easy To Clean
They are generally easy to clean, doing regular cleaning of the rocks makes it easier to clean them and safer. No special equipment is needed to clean them, water is enough but you can add soap if desired. Take the rocks and soak them in a bucket of water for an hour or two. This will remove dirt and debris that has formed on the air spaces inside the rock. Dry the rocks completely before putting them back in the fire pit and lighting it.
Very Low Maintenance
Lava rocks are very low maintenance, washing them can be done after 6 months or after a year depending on usage. Other than cleaning, there’s no other work needed to tend to the rocks. Be sure to cover the pit when not in use to make them last even longer.
Life Expectancy
Due to their high durability, lava rocks can last for several seasons depending on use. They can be replaced as needed, not necessarily after certain fixed intervals. There are other factors to consider when you are looking to replace your lava rocks, frequent maintenance and cleaning will make them last longer. Covering up when not in use shields the rocks from weather extremes also making them durable.

Burning Wood Over Lava Rocks
A lingering question on most people’s minds when choosing a fire pit medium is if you can burn wood over it. When using lava rocks, you can burn firewood safely on top. Before burning wood logs, it’s important to take some precautionary measures. First, add a protective layer made up of lava rock on top of your fire pit, use 4-5 inches to be on the safe side. Place the wood on top of the lava rocks then light your fire pit. Do not light it up without this protective layer as it can be dangerous. It’s important to note that it’s illegal to burn wood in some states, check the respective state laws before attempting to burn.
Different Types
Lava rocks come in different shapes and sizes naturally, some are manually shaped to suit customer preferences. Generally there are different variations but lava rocks mainly occur in the following colours:
- Black
- Grey
- Red
- Brown
You can also find them in different sizes depending on your preferences, here are the various sizes:
- Large
Large lava rocks for fire pit are rather big, they come with an average diameter of about 4 inches or larger. - Small
These are small stones and pebbles with an average diameter of 1 inch. - Crushed
These are manually crushed to make them small and fine. They resemble gravel. - The small lava rocks
With a diameter of 1-3 inches, those are the most popular to use in fire pits and fireplaces.

Prices and Cost Effectiveness
When in comparison with other materials, lava rocks are generally more cost-effective to use as a fire pit medium. The average cost is about $2-$3 per pound. Coupled with their unmatched durability, the lava rocks are worth the investment as you don’t require to buy them frequently as is with other resources.
How Much Do You Need For Your Fire Pit
Knowing the amount of rock needed for your fire pit is necessary for it to function optimally. Too much may hinder burning, too little may lead to damaging your fire pit components. Knowing the right amount is critical as it varies with every fire pit.
The easiest way to know the amount required is by consulting with the user manual that comes with your gas fire pit. In most instances, manufacturers require you use 2-4 inches of lava rock for fire pit.
Vendors sell them in pounds or in cubic feet. One cubic foot weighs on average 25 pounds. You can measure the fire pit to get an accurate reading that you can use as a template when measuring how much lava rock you need.
There are various online calculators that will do the math for you and you will get the exact amount you need to use. Basically, a 24-inch burner plate requires you to use 1 cubic foot of lava rocks, for every 6 additional inches of plate diameter, add another cubic foot of lava rock.
Assembling The Fire Pit With Lava Rocks – What To Do
For the first layer, it is highly recommended to consider the small-sized lava rocks. This provides thermal protection to the gas components and provides a sturdy foundation to place other types of rocks above it.
First, after opening the container, put them in the bucket and wash them with water, this will remove any dust and dirt that may have accumulated during storage and shipping. Rinse the rocks, then place them on top of a towel and wrap. Leave them to dry for a few hours.
Assemble the fire pit correctly and check if the main components are in place, they include:
- The plate is in position, to accommodate the lava rocks.
- The burner is in place and unobstructed.
- The gas is properly connected, and no leaks can be noticed.
If everything is in place, check to see if the lava rocks are dried completely. When dry, place them evenly over the pit, make sure that the stones cover the burner completely. Place the right amount of rocks, being careful not to pile them too thick. Now it is ready to be lit at your convenience.
Potential Dangers
Before lighting your fire pit, it is necessary to check if the rocks are completely dry. Wet lava rocks can pop and explode when exposed to high heat. These explosions can force hot particles out of your fire pit which can be lethal and can cause bodily harm to anyone that is close.
It is recommended that you cover your fire pit when not in use. This will shield the rocks from weather conditions and keep the rocks dry. The hand-made metal covers are generally expensive but a worthwhile investment in the long run because they protect your fire pit components increasing durability.
Regularly check the drain holes to make sure they are not blocked and drain water freely. If they are blocked it will lead to the accumulation of water underneath the rocks and will make the moisture preventing them from drying which can ultimately be fatal. It’s necessary to make sure the rocks are completely dry before lighting a fire to minimize risks and stay safe.
Odors and Smells to Look Out For
When using an outdoor fire pit, it’s necessary to let your nose do some detective work every time you use it. If your fire pit has been installed correctly and is regularly maintained, it should not produce any foul smells or odors. If you smell anything, it’s best you switch it off till you have recognized the smell and what’s producing it. Only use it after you have identified what’s causing the smell and you have done servicing and maintenance.
A rotten egg smell can indicate that your gas is leaking, this can be dangerous, turn off everything and disconnect the gas from the pit and locate where the gas is leaking from. Do not light any matches or switch on any electricity till the threat has been identified. If you can’t identify it, it’s best to call a technician or your gas service provider.
During set up and the curing process, you might notice some fairly strong scents and odors, do not panic or be alarmed because it’s just part of the installation process. Lava rock has a scent naturally and users tend to notice as they are doing the installation.
If your fire pit is generating a burnt or smoky smell, this is just an indication that you need to clean or dust it. Wait for the fire pit to cool before you attempt to clean it and the lava rocks. Use a clean rag to dust and wipe clean the components. Dust is dangerous as it can generate excessive heat which ultimately damages the components of the fire pit.
Where To Buy Lava Rocks
Lava rocks are easily available and accessible. Getting them is not a big hustle as you can walk to your nearest store and find they have stocked them. You can also order the lava rocks online and have them delivered to your doorstep for a very reasonable price:
Use this guide when planning to buy lava rocks for a fire pit for the best results. You could, however, find that fire glass is a better choice for you.