Scoria Rock (Lava Rock)

There might not be a more abundant hardscape material than that volcanic rock.

Since the source of these rocks springs from volcanic activity, they can be virtually found all over the world.

So many factors make it possible for these kinds of stones to come in a number of varieties

. This article will focus on Scoria Rocks and everything you should know when using them within an aquascape.

Quick Stats:
Traditional Name Scoria
Common Names Lava Rock, Cinder, Vesicular Basalt
Origin Extrusive/Volcanic
Habitat Volcano Fields, Intra-oceanic Hot Spots
Color Black, Dark Grey, Reddish Brown
Density (g/cm3) 1.28g – 1.60g
Hardness 3
PH Impact Neutral (No Effect)
Elemental Type Extrusive Igneous Rock (Basalt)

What Is Scoria Rock?

Scoria Rock is an extrusive igneous stone made of cooled magma released from an active volcano.

The common term used to identify the popular stone used in aquariums is Lava Rock.

Other common names used to refer to this stone include Cinder, Vesicular Basalt, or simply Volcanic Rock.

Since this stone is composed of mostly basalt, it has virtually no influence on the environment…

Making it highly favorable for use as a vivarium rock.

Lava Rock "Scoria" Aquascape Tips

Scoria Rock Facts

Scoria is a very easily obtainable rock to acquire and can be found all over the world.

Not only on land near volcano fields but underwater as well.

This type of Lava Rock is so well suited for use in a vivarium that it is frequently used as a substrate as well as filter media.

The dense amount of pores this stone exhibits makes it very easy for bacteria and other healthy microorganisms to form throughout the surface.

This is great for vivarium plants, inhabitants, and the enclosure housing them all.


Volcanic rock, in general, has a predictable look.

Depending on what part of the hardened lava it is harvested from it will have a more or less denser look and feel.

Scoria is a type of lava rock that comes from the second-most outer layer of a magma concentration.

When a volcano erupts, gases rush to the surface of the malted lava.

The lava dries so quickly that large amounts of the remaining gas are trapped in the scoria layers of the magma.

This results in the porous texture found throughout Lava Rock.

A similar type of volcanic rock often confused with scoria is pumice.

Pumice is the layer of dried magma found closer to the surface.

The higher ratio of trapped gas found in this stone will make it lighter and doesn’t sink for a period of time.

The color of Scoria Rock will vary based on which part of magma it is removed from as well as the sedimentary minerals it’s mixed with.

Lava Rock colors will range from black to dark grey, to even a reddish-brown.

The black and grey lava rocks contain high concentrations of iron and magnesium.

The red or brown color Lava Rocks are the same minerals that oxidized during the cooling phase.

All forms are usually safe for aquarium use.

Pumice, on the other hand, is either white or light grey.


As we sort of touched on earlier, the origin of Lava Rocks is found anywhere there is, or has been volcanic activity.

Most volcanic fields are usually found throughout island-type settings but it isn’t uncommon to see them in artic areas as well as the deep sea.

Different geographic locations will also present slightly different-looking Lava Rocks.

Igneous rocks generally form in two ways, under the earth’s crust (platonic) or above the surface during an eruption (volcanic).

Scoria forms at the earth’s surface, hinting at why we call it a volcanic rock.

Environmental Influence

Since Lava Rock is technically artificial in nature, it has no real environmental impact.

Even though Scoria is considered a basic type of igneous stone, it is still inert.

Making these rocks are suitable for freshwater use as well as saltwater enclosures.

I would recommend cleaning any newly acquired Scoria Rock to assure there aren’t any potentially hazardous minerals trapped within the stone though.

This rock has the tendency to leach dust and other unwanted bits of loose debris when it isn’t presoaked before use.

Vivarium Preference

As I mentioned earlier, Scoria is great for all types of vivariums.

Plants generally benefit from the types of metals this rock is made of so it would do fine in freshwater tanks.

If you notice a slight increase in water hardness using red or brown colored Lava Rock, try buffering it with driftwood will bring the hardness down.

Personally, my rule of thumb with preference is red-colored Scoria for saltwater aquariums because it contrasts coral well…

Black and gray-colored Scoria for freshwater tanks for the contrast with vivarium plants!

The use of Lava Rocks in vivariums has been a common practice for quite some time now.

When using it as a hardscape rock, large pieces can be assembled in an iwagumi fashion.

Smaller pieces work great as a substrate for plants to root through or just as a drainage layer for most terrarium setups.

The ability to house healthy bacteria also makes Scoria excellent as a filter media as well.


Igneous Rocks like Scoria have what seems like an infinite amount of advantages when it comes to using them in an enclosure…

Many of which we have already covered. It’s a great vivarium rock that has neutral effects on the surrounding area.

Scoria is rich with surface space due to its rigid texture which is ideal for bacteria.

It’s a lightweight stone that can be back stacked, broken down into smaller parts, or combined into a custom-shaped hardscape.

The range of available colors also makes it a good stone to consider when building a tank from scratch.


When it comes to the disadvantages of using Scoria in a vivarium, there really isn’t much to complain about.

Lava Rocks are one of the easiest igneous stones to work with.

One thing to note is it can be quite messy to handle.

On the initial handling of the rock, you will notice that it will produce quite a bit of dust.

If it is placed directly into an aquatic enclosure prior to cleaning, it can leech unwanted particles.

Buy Scoria Rock

Lava Rock is one of the easiest stones to acquire.

It is generally sold in most hardware supply or garden stores.

When buying Scoria, consider the source and be sure it is what is listed in the description.

This rock is easily mistaken for pumice and other types of basalt.

No two pieces will look alike but they should still have many of the characteristics listed in this article.

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

Scoria Rock Recommendations

When it comes to working with Scoria Rock for the first time, there are a few things worth keeping in mind.

What kind of pieces you have and how much of them should be used are important factors.

Preparing this stone for an enclosure is also a valuable step that will ensure longevity.

Also, making sure there aren’t unwanted elements tucked within this stone will also aid in preventing unwanted fluctuation of the custom habitat will also be recommended.

Here are a few steps below to better understand the management of Scoria:

Cleaning Scoria Rock

In most cases, newly acquired Scoria Rocks will need slight preparation before going into a vivarium.

This will matter more for aquariums, ripariums, and paludariums rather than terrariums since unclean stones will cause water to change color.

Begin by placing stones in a bucket of cold water.

Lightly rinse each stone thoroughly with a medium-pressure hose.

If needed, use a bamboo skewer to assist with breaking up debris trapped in small crevices.

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

Breaking Scoria Rock

Scoria Rock is one of the easiest aquascaping rocks to break into smaller pieces due to its low-level hardness score.

In many cases, the hobbyist will simply bash a towel-covered piece of rock with a large hammer.

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

Save the smaller undesirable pieces for a project later down the line.

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

Chiseling off parts of the rock is a more controlled way to break Scoria into desirable pieces.

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

Also, reclean rocks as needed once they are broken.

Rocks Similar To Scoria Rock

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

Scoria is relatively easy to find so it shouldn’t be hard to have plenty of it to work with.

Furthermore, if you want to consider something different…

There are a wide variety of stones to contemplate.

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

Sandstone "Quartzarenite Rock" Hardscape Guide
Marble Rock "Metamorphic Limestone" Hardscape Guide
Strata Rock "Sandstone" Hardscape Guide


Scoria was one of the first vivarium rocks I had any sort of experience working with.

This stuff was very forgiving and tolerated a lot of trial and error in those days.

I recommend always keeping an extra bag on hand since it has so many uses.

The variety of colors, neutral impact on vivariums, and raw texture make Scoria rocks one of the best stones to work with.

If you are considering this rock for the first time, how do you feel about it now that you’ve read this guide?

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