Can fire pit rocks explode?

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Max Firepits

Do fire pit rocks explode? It's an important question that you need to consider before firing up your camp fire. in this article, we explore the different types of rocks and see which ones to use and which ones to avoid.

Can fire pit rocks explode?

I would say that every week here at MAX Fire Pits, we get about 20 emails and phone calls asking the same question; “Can fire pit rocks explode?”

As we all know, outdoor fire pits offer a unique blend of warmth and ambience, inviting us to gather for stories, laughter, and marshmallow roasting. However, there lurks a potential danger many of us overlook: the danger of exploding rocks. Yikes!

After all, spending a night around open fires is meant to be relaxing, and the last thing you want to watch out for is danger when you sit around.

Key Takeaways

  • Granite and lava rocks are safe for use in fire pits.
  • Porous or wet rocks can trap water and cause explosions when heated.
  • Always use dry, non-porous rocks to ensure fire pit safety.

Why do rocks even explode?

At the heart of this problem is water — specifically, water trapped within the pores and cavities of particular rock and stones. When heated, this water expands rapidly, exerting pressure from within. This can cause rocks, particularly porous varieties, to shatter violently in a camp fire, sending fine, sharp pieces of rock shrapnel flying​ into the air. 

Sedimentary rocks like limestone and sandstone, along with some volcanic and metamorphic types, are most likely to explode due to their structure, which can easily trap moisture, quickly turning to steam and pressure. Any smooth rock sourced from a river can become dangerous when it gets hot in a firepit or open fire.

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.

Here’s a quick list of which rocks to avoid:

– River rocks

– Wet rocks

– Basalt

– Stones from a river bed

– Sandstone

– Concrete

– Pumice

River rocks, often rounded from years of water erosion, are remarkably deceptive. Despite their smooth appearance, they may harbour significant moisture and are thus highly explosive when heated in a fire pit or campfire. 

River rock is also usually pretty easy to obtain, so it seems like a quick and easy solution. However, it has a high tendency to explode, so we suggest you avoid it at all costs.

lava rock

Choosing Safely: Rocks That Won’t Turn Your Fire Pit into a Hazard

In contrast, denser, non-porous rocks like granite, marble, and slate offer a safer choice. Their compact structure makes them less likely to absorb water, reducing the risk of explosions. Manufacture options like lava rocks and fire glass provide a reliable and attractive alternative for those seeking added peace of mind. 

Lava rock and stone, formed from cooled molten lava, naturally withstand high heat. However, they can still pose a risk if they become wet. Similarly, fire glass is designed to endure extreme heat without exploding, adding a modern touch to your fire pit with its reflective beauty.​ 

Rocks that are less likely to explode with heat:

  • Granite
  • Lava rock or stone
  • Marble
  • Slate

Remember, if in doubt, always talk to a professional who is qualified to give advice on what rock to use.

Prevention is the most important.

Preventing rock explosions starts with selection and maintenance. 

Dry your rocks thoroughly before use, and consider ‘curing’ new lava rocks by applying heat slowly to release any trapped moisture safely. This process involves placing the stones in your fire pit, lighting it and allowing it to burn for up to 45 minutes under supervision. Watch for any sign of steam or cracking or if the rock starts to break.

Regular checks for moisture and avoiding using rocks recently submerged in water can further reduce any issues.

Bringing It All Together

An outdoor campfire can be the heart of your garden, a place for relaxation and socialisation. Understanding the risks associated with certain types of rocks and taking steps to reduce these dangers can ensure your fire pit remains a safe, enjoyable feature of your outdoor space. 

Remember, the key to fire pit safety lies in choosing the suitable materials and carefully maintaining your setup. This way, you can enjoy the warmth and charm of your fire pit without worry.

Disclaimer: We are not qualified to advise you on what rocks to choose. This article is a rough guide based on sources gathered from the internet. We are not responsible for rocks that may explode. Please consult a qualified professional before deciding which rocks to use in your campfire.

Want more information on fire pits? Check out our Ultimate Fire Pit Guide for all the tips, tricks and expert knowledge on getting the most out of your fire pit.



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Can fire pit rocks explode?

Do fire pit rocks explode? It’s an important question that you need to consider before firing up your camp fire. in this article, we explore the different types of rocks and see which ones to use and which ones to avoid.