Travertine vs Sandstone

From time to time we create articles that look at materials and compare two of them with one another. These comparisons allow us to comment on the properties of each material and highlight differences in the way each of them is used. In this installment of this type of article, the topic will be travertine vs sandstone. We will briefly discuss some of the characteristics of travertine and sandstone and we will explore how these materials are similar and how they are different from one another.

Travertine Overview

Travertine is a natural stone that is distinct in its appearance. Once you have laid your eyes on this material, you will be able to easily recognize it when you see it. But what is travertine? Simply put, travertine is a specific form of limestone. To find out more about limestone, you can check out our article entitled: Limestone Surfaces. Travertine forms in the presence of water. In particular, travertine forms around the mouths of caves or in the midst of hot springs. The minerals from which travertine forms precipitates to make this enigmatic rock. So, that's what travertine is. But what are its properties?

The Hole Travertine Story

Since travertine forms through a process involving precipitation, the stone is characterized by holes that are noticeable to the eye. These holes give the material its distinct appearance and make it truly unique as far as looks go. These holes (also referred to as pits, voids, pores, or pockets) are often times filled during the manufacturing process. A color complimentary to that of the stone is often used. Although, sometimes a clear filler for travertine is used. These travertine fillers not only fill the voids we are talking about here, but they also strengthen the stone as well. This results in a material that is not only beautifully elegant, but also resistant to cracking. It is safe to say then, that travertine is a porous natural stone. Yet, there are sealers for natural stone, including travertine, that drastically slow down its absorption of water and oil. This helps the stone resist potential stains that it could receive from these kinds of liquids.

The Hard(ness) Truth About Travertine

Another aspect of travertine that is worth noting is the hardness of the material. Or rather, the soft nature of it. Since it is composed primarily of calcium carbonate, travertine is found on the Mohs scale of mineral hardness at around 3 to 4. The scale goes all the way up to 10 (with 10 being the hardest). So even at 4, travertine is on the soft end of that scale. The softer the material the less scratch resistant it is. That doesn't mean that soft stone such as travertine is not useful. On the contrary, travertine is used for all sorts of applications, including floor tiles. So, even though we say that travertine is "relatively soft", it is still rock and is suitable for quite a few uses.

Travertine's Color

Although many colors of travertine exist and it forms in a variety of colors, the most frequently seen colors are brown hues such as beige, taupe, tan, and cream. It also forms in pretty much all shades of gray. Gray and brown hues are the most commonly seen colors and the fillers used are often complimentary to these colors, or a transparent filler is used to highlight the natural porosity. Keep in mind though, that travertine does form in many colors beyond the gray and browns mentioned here.

Sandstone Summary

Sandstone is a sedimentary rock that, as its name implies, is made up of sand. Sandstone forms when some substance acts as a "cement" material and bonds the grains together. Sand is made up of silica. That means that sandstone is considered a siliceous natural stone. As a general rule, siliceous stone is harder than calcareous stone, which is rock that is characterized by its high calcium carbonate content. Simply put, sandstone is a mass of strongly bonded particles of sand that form a solid material.

Like travertine, sandstone is a natural stone. As a natural stone it is similar to travertine in some ways, yet different from travertine in others. Like we did with travertine, we will look at the properties of sandstone and talk a little bit about them. As we do, we will comment on how the trait under discussion plays a role in the stone's use.

Sandstone's Hardness

Since silica is much harder than calcium carbonate, it stands to reason that sandstone is harder than travertine. But just how hard is sandstone? Well, on the Mohs scale it can range anywhere from 6 to 7. So, in contrast to to its counterpart, it lies above the midway point of 5. Thus, it is considered a hard stone. The harder a stone is, the more resistant to scratching it is. However, cutting hard stone slabs requires diamond blades for hard stone. Blades made for cutting granite and/or quartz are often times suitable for cutting sandstone. We recommend though, checking with the blade's maker to ensure that any blade you select is well-suited for cutting a specific material. The hard truth about sandstone is that it is scratch resistant and therefore, considered durable.

Porosity of Sandstone

Another characteristic of sandstone is that it is porous to one degree or another. Like many other natural stones, sandstone's porosity varies from one slab to the next. This variance tends to be wider in the case of sandstone. Why is that the case? The answer has to do with how this rock is related to yet another natural stone called quartzite.

We won't get into the details of quartzite here, but the short explanation is that sandstone transforms into quartzite through metamorphosis. One of the properties that changes in the process is the stone's porosity. That is, the material gets more dense as it transforms into quartzite. Since the transformation takes so long, and since the process is slow from our human perspective, there are many degrees of porosity during which the material is still technically sandstone, but is in the process of becoming quartzite. Depending on where a particular slab was in metamorphosis when it was quarried and processed, the porosity will either higher or lower. However, like we said earlier, sealers are available for reducing the absorption of water and oil based liquids. Natural stone sealers applied regularly make the porosity less of an issue. Yet, it is important to note that cleaners not made for natural stone destroy sealers and remove any benefits the sealer provides. Thus, it is important that only cleaner formulated for natural sandstone be used on the material. That way, the sealer that you apply is not stripped right off after the first cleaning and wasted.

Color Selection

If color selection is important to your customers, this aspect of sandstone's properties is no doubt of interest to you. What colors of sandstone are there? Well, to put it simply, whatever colors of sand you see, there is probably sandstone in that color. That makes sense, right? Sandstone is made up of sand, so whether it's white sand, red sand, beige sand, or brown sand, sandstone has likely formed from that color of sand.

Similarities & Differences of Travertine & Sandstone

Now that we have talked a little bit about each of the materials we are comparing, it should be easier to see how travertine and sandstone are similar. Furthermore, identifying how these materials are different takes only a little effort.

How They Are Similar

As natural stone, both travertine and sandstone are porous to a certain degree. So, each of these materials should be sealed using natural stone sealer to help reduce the absorption rate. As we mentioned in the discussion, porosity varies from one stone to the next; even if the two are the same type of stone. Additionally, each of these materials needs to be cleaned using a natural stone cleaner. These are formulas that are pH neutral and won't harm the existing sealer on the stone. Virtually every natural stone is porous to on degree or another. So that means no matter what natural stone you are caring for, it more than likely is similar to both of these materials in this way.

Their Differences

The composition of these materials is the main reason for their differences. As we mentioned, that travertine is calcareous (composed of calcium carbonate) and sandstone is siliceous (composed of silica). Since the stone is only as hard as the minerals of which it is composed and silica is harder that calcium carbonate, well, you get the point. It is easy to see why sandstone is harder that travertine. Nevertheless, both sandstone and travertine are hard enough to use as countertop, flooring, and wall tile materials.

We would be remiss if we did not speak about perhaps the biggest difference between calcareous and siliceous materials. Calcium carbonate is a substance that reacts with (neutralizes) acid. In fact, many antacids that people consume to relieve heartburn are made from calcium carbonate. This means that a stone surface that is made of calcium carbonate (i.e. travertine) will react with acidic substances. As a result, travertine is best used in applications where it will not be exposed to acid. The reaction between calcium carbonate and acid results in the acid being neutralized at the expense of the destruction of the calcium carbonate. Because of this, you may hear people say that acid "eats" travertine (or some other calcareous stone) and this is what they are most likely talking about.

Since the mineral is actually destroyed, you may be inclined to think that these types of reactions (referred to as "etches" or "etching") cannot be fixed. However many etch marks can be "removed" in the sense that the difference in the appearance of the surface can be blended so that the discoloration is not as dramatic or obvious. In fact, many people that have uses etch remover are astounded at the results.

Well that will wrap up our look at travertine vs sandstone and the differences and similarities between them. In the end, the material used by you or your customer will depend on many factors. Knowing the details about the materials you select will help you to make an informed decision about which of the vast stone choices is right for a given project.