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Concrete vs Onyx Countertops

Two materials that share some interesting properties and that are found being used as countertop surfaces are concrete and onyx. The materials are also different from one another in specific ways. In this article we will explore the comparisons of concrete vs onyx. Knowing the similarities and differences helps the consumer to know just how to care for and maintain the material. As we compare these materials with one another, we will see how the various properties play a role in the use of each type of surface.

A Concrete Use for Countertops

It goes without saying that concrete is a versatile material. Just think of all the different uses there are for this material. It can be shaped, colored, molded, and painted. It used many surfaces including driveways and sidewalks. So its durability is well established. However, it catches some by surprise to learn that this material also is used for countertops. Concrete countertops are intriguing because they may take on different forms, and even resemble works of art. So let's take a stroll and consider some of the properties of concrete countertops.

Concrete's Hardness

As previously mentioned concrete is a hard material. In fact, it can be made with various hardness. Depending on the mix, concrete can achieve a hardness of around 7 on the Mohs scale of mineral hardness. That means that it is a durable material and when it is used for countertops, it has the potential to last a long time.

The Color Selection of Concrete

Looking at the subheading above, you may be thinking, "that's easy, it is gray." That's true. Most concrete is some sort of gray color. However, it can be dyed with virtually any color the consumer desires. Simply mixing coloring pigments into the concrete allows for all sorts of artistic variation.

Porosity of Concrete Countertops

By its very nature concrete is porous. You can see as much when it rains. The moisture from rainfall soaks into surfaces made from the material. Countertops made from concrete are also absorbent and this means that they can stain if colored liquids spill on them and get into the pores of the material.

Shining a Light On Onyx

The natural stone that we are referring to as onyx in this article is actually what geologists would refer to as "banded calcite". This stone is actually a relative of the familiar material called marble. There are a number of materials that are composed primarily of calcium carbonate (or calcite). These are collectively known as calcareous stone; onyx is one of these. The fact that these materials contain calcite means that they share some common characteristics. Let's look at some of those now.

Onyx is Relatively Soft

One trait that calcite brings is a relatively low measure of hardness on the Mohs scale. Calcite, the main component of onyx, measures at about 3 on the Mohs scale of mineral hardness. This is the low end of that scale. What this means is, onyx is relatively soft as far as stone is concerned. That doesn't mean that it isn't adequate for use as a countertop material. In fact, much of the banded calcite has a property that makes it a great choice for very prominent fixtures in certain designs. Let's look at that property now.

Onyx's Color is Fascinating

As we mentioned above, onyx lives on the softer end of the Mohs scale. Yet is is one of the few natural stones that allows light to pass through it. This translucency makes it a material that really stands out in certain settings. For example, the front panels in a bar might be made from onyx tiles and have backlighting that shines through them. This effect really makes the color of the fixture noticeable; particularly when the rest of the room is dimly lit. If you have ever seen backlit onyx, it is amazing and memorable.

Absorbency of Natural Onyx

Since onyx is a natural stone, it has a measure of absorbency. Thus, it is recommended to periodically use a sealer to keep water and oils from making their way into the pores of the stone. This is what causes stains to develop and then a stain remover would be needed to take the stain out of the stone. Additionally, sealers are good as long as they are not removed and using the wrong stone cleaner on a countertop removes stone sealers very quickly. Because of this we recommend using cleaner for natural stone surfaces. A pH neutral cleaner is best.

Concrete and Onyx Comparison

Moving into the comparison of concrete vs onyx, let's look first at the similarities.

Similarities Between Onyx and Concrete

These materials are similar in that they are both great for use in creative style designs. The fact that concrete can be molded and colored makes it very flexible and it can be incorporated into virtually any design. Yet, it does require a specialist to install it and the more elaborate the design, the more costly it may be.

Onyx too is a material that is well-suited for creative works. As we discussed earlier, it is a very appealing element when used in front of a backlight. Backlit panels made of onyx have been used for all sorts of features including:

  • Bar Panels
  • Bar Countertops
  • Step Risers
  • Wall Accent Panels
  • Floor Panels

Both Materials Need Sealed

Both concrete and onyx have a measure of porosity and therefore need to be sealed. This is something to keep in mind when making you care and maintenance plan.


There are many differences between these materials, but perhaps the most notable is the hardness of them. We mentioned earlier that concrete is pretty hard and that onyx lives at the low end of the Mohs scale. This hardness difference means that specific saw blades may need to be used for each type of material. Diamond blades for cutting hard stone are what is needed for concrete if it needs to be cut once it is formed into a countertop. On the other hand, cutting onyx may be best accomplished using a marble blade.

As we have seen in this concrete vs onyx comparison, there are a number of traits that are worth noting. We looked at the similarities between the two and we took note of the main differences. In the end though, either one might be a nice material to use for a countertop. It just depends on what your project calls for in the design.

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