What Rocks Should Not Be Used in a Fire Pit? (2024)

There are many ways landscaping stones can be used in outside spaces. If you have a fire pit on your property, these attractive hardscaping materials can certainly make an appealing and functional addition to this particular spot. However, it’s just as important to keep safety in mind. For this reason, the team from RS&P Rocks Stones & Pebbles, the experts in how to properly and safely use decorative rocks, from pure gold river rock to white pebbles, take a moment to go over the rocks you shouldn’t use in a fire pit.


Limestone is a porous rock often used safely in fireplace hearths. For this reason, it’s assumed to be an equally safe choice for fire pits. However, things that happen commonly outdoors but don’t tend to occur inside—such as rain—can be a potential safety risk. When rainwater falls on limestone, it’s absorbed into the rock itself. This presents the possibility of a dangerous combination of water and fire.


Available in a wide range of colors that include gray, white, red, and blue, sandstone rocks can work well in gardens and other exterior locations. The problem with putting them in fire pits is that they’re extremely porous, meaning they hold water on the inside well, and there’s the possibility of an explosion when they’re exposed to heat. Plus, these rocks don’t hold up well when exposed to heat for long periods, such as what’s common with a regularly used fire pit.

River Rocks

Don’t get us wrong, we love river rocks such as polished black river rock. These attractive, naturally formed landscaping features are ideal for use in many places. The downside when it comes to fire pits is that since these rocks spent several years resting at the bottom of riverbeds, they likely contain a lot of water deep within them. This presents the same dangers associated with the two types of rocks mentioned above.


Formed by the mix of hot volcanic lava and water, pumice is full of cavities. It’s also widely used for cleaning when there’s a need for extra abrasion and for smoothing out various surfaces. However, the cavities in these rocks are often filled with water, and the high heat in a fire pit could result in a potentially dangerous explosion.

Pea Gravel

These rocks are on the small side. The problem with the smaller size of pea gravel is that the rocks usually don’t heat up evenly, which could cause some problems with the flame in your fire pit. Pea gravel also has a tendency to pop when exposed to high temperatures.


Soapstone is unique among rocks in that it’s on the softer side. The main reason this is the case is because these rocks are a mix of various materials, including micas, carbonates, and amphiboles. In addition to being prone to holding water, soapstone is also not hard enough to stand up well to being used in a fire pit.


A volcanic rock, basalt is a mix of quartz, iron ore, and similar substances. It’s formed under extreme heat, which is why it has a darker hue. While attractive for other landscaping uses, basalt is generally not a rock you want in your fire pit. The main reason is because of the possibility of explosion with exposure to high heat due to the water that often accumulates inside.

For advice on how to properly use decorative rocks in your landscape, reach out to the experts at RS&P Rocks Stones & Pebbles, a premier landscape rock and supply superstore. We specialize in drought-tolerant landscaping materials, including a variety of colored river rock and Mexican beach pebbles. To learn how we can help you enhance the character and beauty of your outdoor space, call us today at (866) 380-0770.

What Rocks Should Not Be Used in a Fire Pit? (2024)


What Rocks Should Not Be Used in a Fire Pit? ›

Concrete blocks, pea gravel, river rocks and other materials that are often used in DIY fire pits can trap water inside. When they are heated up, this can cause an explosion.

What rocks should not be used in a fire pit? ›

What rocks to avoid? To mitigate this risk, it's crucial to know which rocks to avoid. Porous rocks, including limestone, sandstone, pumice, and shale, are notorious for absorbing water and should be avoided in your campfire. River rocks, often rounded from years of water erosion, are remarkably deceptive.

What kind of rocks to put in a fire pit? ›

Limestone is another common choice for fire pit construction. It is durable, heat-resistant, and available in a range of colors and textures. Limestone can add a touch of elegance to your fire pit design.

Why not to use river rocks for fire pit? ›

Crucially, don't ever use river rocks. There are several reasons why you should never use river rocks for a campfire, with one of the most obvious being that they are often more porous and can contain water. When this water gets hot it creates steam and the rapid expansion can cause the rock to explode.

What rocks are safe to heat? ›

Granite can withstand higher temperatures compared to many other rock types, and the heat transfers well through the rock making it good for cooking up different kinds of food, from meats, seafood, veg and dough based products. Granite can also withstand low heats too, meaning it can cope with being stored outside.

Can I use any stone for a fire pit? ›

There are different kinds of natural stones, each of them with unique characteristics. However, not all of them may be fit for a fire pit. Stone fire pits should be built with natural stone boulders that are strong and offer a variety of designs.

Are glass rocks or lava rocks better for fire pits? ›

The glass pieces are non-toxic and will not leave behind any ash or soot, which is great for keeping the outdoor area clean. Lava rocks, on the other hand, are known for being very porous and light. Due to the porous texture, they contain no moisture – and do not hold any heat in.

What is the best thing to put under a fire pit? ›

The best materials to put in the bottom of your fire pit are gravel, paver base or fire bricks.

What is the best fire resistant stone? ›

Among all the given options sandstones, especially the compacted type has more fire-resisting properties.

Can you use landscape lava rock for fire pits? ›

All lava rocks is considered good for fire pits, they come in red, and black lava rocks with the option to have either color rolled/tumbled for a refined look. There is no grey lava. This is a common misconception. Black lava looks grey with use.

Is limestone good for a fire pit? ›

The short answer is yes, you can use limestone for a fire pit. Limestone is a natural stone that is able to withstand high temperatures, making it a safe and practical choice for building a fire pit.

Is granite good for fire pits? ›

Granite is an extremely durable material that can be used safely for fire pit designs. It's a great choice for a fire pit and there are many types of granite that can be used. Granite blocks, crushed granite, and decomposed granite are all types that can be used in parts of your outdoor fire pit.

What is the most heat resistant rock? ›

Amongst all natural stones, granite offers the best heat resistance.

Are all rocks fireproof? ›

Not all rocks are suitable for use in a fire pit, so make sure you check the type of stone before using it. Porous or wet stone, such as sandstone or river rocks, may crack or explode when they reach high temperatures.

What are the best heat resistant rocks? ›

Dark igneous rocks such as vulcanite, gabbro, peridotite, basalt, and granite are excellent choices. Mixed type such as the gabbro-diabase is also very common and found in nature. Vulcanite is good for its high metal content, which helps it store heat very efficiently.

Can you use patio stones for fire pit? ›

Make sure to choose pavers that are rated for outdoor use and can stand up to the elements. 3. Sand: A layer of sand should be spread at the bottom of your fire pit before you lay down the pavers. This will make them adhere better and prevent them from shifting around over time with the heat from your fire.

Can you use regular rocks in a gas fire pit? ›

For gas fires, fill the fire pit with enough lava rock to at least cover the fire ring. Do not use rock or gravel of any kind in place of lava rock; it can potentially explode when heated. There are, however, some special glasses and ceramic “stones” that you can use.

Can you use glass rocks in a fire pit? ›

Exotic Glass is perfect for use in all natural gas or propane fire pits and fireplaces. Always refer to manufacturer instructions when considering fire glass in pre-assembled propane fire pits. Do not use Exotic Glass in wood burning fire applications!! How much glass should I use in my fire pit or fireplace?


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