Travertine vs Onyx

In discussing natural stone materials used for hard surfaces in homes, businesses, and other architectural projects, there are several materials to consider. Two such materials are natural travertine and natural onyx. In this comparison of travertine vs onyx we are going to examine some interesting information about both of these materials. And the information we consider and what it means may surprise you.

A Foundation for Comparing Travertine and Onyx

Often times, comparing two materials involves considering the similarities and differences between two materials by looking at the properties of the materials and explaining how those properties compare between the two materials. Performing the comparison in this manner highlights the uniqueness of one or both of the materials from other stone and from one another. In the case of travertine compared with onyx though, we are going to take a slightly different approach. We will first lay a foundation by describing how these stone materials are alike, explaining the significance of the information along the way. Then, we will explain how these materials differ and what it means in terms of practical uses.

Similarities Between Travertine and Onyx

It is not often that we get to begin a comparison between two stone materials by saying that the two materials are two variations of the same stone. But in this case, that is exactly how we describe travertine and onyx. They are two versions of the same material. Note how geologist Karin Kirk expressed it in the article entitled Know Your Rocks: An Overview of the Geology of Natural Stone. In that article Karin says the following:

Onyx and travertine are variations of the same stone.

So what are the similarities between travertine and onyx? Well, both materials are composed of calcium carbonate in the form of calcite. That is to say that both travertine and onyx are made of the same thing. This is our first similarity.

Similar Reactions to Acid

Two stones being composed of the same mineral mean they react the same way when exposed to various other substances. Travertine and onyx both react to acid in the same way. Calcium carbonate (the mineral both stones are made of) reacts with acid. During the reaction, the acid is neutralized and the calcite is dissolved. When this reaction occurs on a surface made of any calcite based stone, the result is what is referred to as an etch. The etch manifests itself as a dull spot on polished surfaces or as a dark spot on honed surfaces. In either case, the spot is the result of part of the stone being dissolved. Thus, changing the appearance of the stone's finish.

Travertine and Onyx Similarly Used

Travertine and onyx are both used for decorative purposes. That is not to say that they cannot be used for surfaces, but they are relatively soft as far as stone goes. This property along with the fact that each stone etches, means that you usually see these materials used in places other than a kitchen countertop. Both travertine and onyx work well as accent material. For example, stone backsplashes, table tops, and bathroom vanities are some examples of where you might find these stones. Onyx is used as lighting fixtures and travertine wall and floor tiles are not uncommon.

Similar Formation Process

At the outset of the discussion we stated that these two materials are variations of the some stone. We said that because both materials come from water that is loaded with the mineral calcite. One place you find this kind of water is at the mouth of a hot spring. Travertine precipitously forms at locations like this. Similarly, natural onyx forms in locations like the one just mentioned. However onyx form in cool water as well. Yet, just because these two materials are made of the some minerals, are used for the same things, and form in the same types of locations does not meant they look alike. In fact, travertine and onyx look different and each one has its own distinct feature that makes it easily identifiable.

Differences Between Travertine and Onyx

At this point you may be thinking to yourself, "sounds like these two materials are pretty much the same". But that would be like saying that whipping cream is the same as sour cream. Technically, they are both the same substance, but in a practical sense they differ enough that they are called two different things. It is similar with travertine vs onyx.

Visible Trait Difference

One of the most easily noted differences between travertine and onyx is that fact that each has what some might refer to as an identifying mark. These marks make each of these calcareous natural stones easy to identify. Let's look at each one in turn.

Distinct Travertine Trait

In the case of travertine, it is the voids (also called pits, holes, and pockets) throughout the stone. In essence, travertine looks as though it is a sort of mineral foam that has solidified. The holes in a travertine tile are often filled in during the processing of the material. By filling in the voids, the surface is leveled and strengthened. Various fillers are used for this, including adhesive fillers that are very effective for this. Using a color that compliments the stone's natural color is a common method. Clear products can be used as well. These fill the holes and strengthens the stone, but preserves the natural appearance of the voids in the material.

The Characteristic that Distinguishes Onyx

Like its countert-part travertine, natural onyx (what a geologist might call banded calcite) has a distinctive appearance that makes it readily identifiable. That readily identifiable trait is that in many, many cases, it has translucent bands of color throughout the material. These bands offer a spectacular feature that allows onyx to be backlit.