Natural Serpentine
In the realm of natural stone, there are some materials that have clear definitions. They have a specific name and the traits of the material are distinct and clear. Yet, there are other materials in the natural stone industry that have several names. At times information that is presented regarding these multi-named stone materials can become confusing. Serpentine stone is one of those materials. In this article we will talk about this remarkable natural stone. We will also explain why it gets misunderstood. Additionally, we will explore some of the properties of serpentine and discuss how the material is used.
What is Serpentine?
Serpentine is a natural material that has a very technical definition. The definition from Geology.com is as follows:
Serpentine is not the name of a single mineral. Instead it is a name used for a large group of minerals.
As you can see from the quote above, there are a number of minerals that show up in serpentine stone. As long as the stone is composed of minerals from the appropriate group, it is serpentine. And much like other natural stone, the mix of the minerals in a given stone will have a bearing on its appearance to a certain degree. But what minerals make up a slab of serpentine?
Serpentine's Composition
Every kind of stone is geologically defined by the mineral content, the way it forms, and other details as well. As far as serpentine goes, it is composed of various minerals as the website above states. That same site goes on to say the following regarding composition:
...it is a name used for a large group of minerals that fit this generalized formula:
(X)2-3(Y)2O5(OH)4.
In this formula, X will be one of the following metals: magnesium, iron, nickel, aluminum, zinc, or manganese; and, Y will be silicon, aluminum, or iron. The appropriate generalized formula is therefore as follows:
(Mg,Fe,Ni, Mn,Zn)2-3(Si,Al,Fe)2O5(OH)4.
Wow! That is some variety. In fact the appearance of serpentine will vary across a range of looks, textures, and porosities. However, the one very consistent trait this material has is that it is nearly always a shade of green. Like soapstone, and quite a bit of slate, serpentine is a greenish color. The mineral that you do not see in the list above is calcite. This is important because the absence of calcite in serpentine is what separates it from the calcareous family of stone. Marble, limestone, travertine, and banded calcite (usually referred to in the stone industry as onyx) are all calcareous. But serpentine is not calcareous and therefore is technically not in the same family as the aforementioned materials.
Even though, serpentine is not calcareous, you may at times find that a serpentine stone is called "marble". Green marble, "hard soapstone", and other labels are used for stone loaded with serpentine minerals. Yet, there are some specific differences between serpentine and marble. While we won't get into them here, you can read about the comparisons in another article here on our website entitled: Marble vs Serpentine.
Properties of Serpentine
Since serpentine is composed of so many different minerals, it varies in hardness, porosity, and other characteristics. Here though, we will briefly cover some of the common properties of serpentine. As mentioned above, it is green in color. However, the shade, brightness, and luminosity of the green is different based on which minerals a particular stone is composed of.
The hardness of serpentine generally ranges anywhere from 3 to 6 on the Mohs scale. That means you may find some serpentine slabs that are around the same hardness of marble. Could this perhaps be a reason why serpentine sometimes gets called "green marble"? At any rate though, other stones may be as hard as a 6 which is up there close to natural granite. The point here is that you will want to get to know the particular stone you are choosing so you won't be surprised after it is installed. Be sure to ask what the hardness is or do a scratch test to find out how hard it is. If you do a scratch test, be sure to test the various parts of the stone since it is composed of multiple minerals.
How Serpentine is Used
As we have mentioned up to this point, true natural serpentine is a material that can be almost as hard as natural granite depending on which minerals a particular slab contains. It also is not a calcareous stone so it is not susceptible to etching like true green marbles it is sometimes mistaken for are. Thus, serpentine is actually a great material fro kitchen countertops and even exterior building tiles. Of course, other applications are well suited for serpentine as well. But it is worth noting these two since kitchen countertops are subjected to acidic liquids and fairly sharp utensils. And building exteriors are exposed to acid rain in some areas.
As we have seen in this article, serpentine is a material that carries with it an interesting bit of substance. Knowing what this material is will help you to not only guide your customers, but also work the material effectively in your shop.
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