Getting to Know the Various Types of Stone
There are many different types of stone or stone-like products available in today’s market place. These items are composed of unique materials that have undergone both geological and man-made processes before being fabricated into a finished product for your home. But what do you know about these materials? Where did they come from? What kind of stone should you choose? Which of these materials would best suit your particular needs?
While looking for your stone product, you probably have heard of many different kinds of stone or stone-like materials. For example, marble, granite, quartz, maybe even soapstone or onyx. Each of these is an amazingly unique material that will exceed your expectations when used in the correct setting.
The simplest way of describing many of these products is whether they are a Natural Stone or a Man-Made Stone. Natural Stone is any rock found in nature that is used for building or decorative purposes and like all rock, it was formed by natural geological processes over thousands, millions or even hundreds of millions of years. Every piece of natural stone is a wholly unique blend of colours and minerals. Each type of stone will have its own specific of properties. The most common types of natural stone are granite, marble and limestone, but there are a few others that are often used in residential applications – quartzite, soapstone, travertine and onyx.
The vast majority of Man-Made Stone can be divided into one of two types, Engineered Quartz slabs or Porcelain slabs. Each of which have been fabricated using specific and often closely guarded manufacturing processes to ensure that both types will perform as per the design criteria of the manufacturer.
If a stone was formed by volcanic activity or melting, we call it a “Magmatic” stone. Granites are an example of magmatic stone. These stones were formed when liquid magma cooled and became very hard. All granites are also ”Siliceous” stone, which means they are composed from silicates like feldspar, mica and quartz. Some granites have veins through their composition which are the result of unique metallic crystals that were deposited along with the mineral crystals in the magma. Other granites were formed when different magmas blended together before they hardened. The exact mix and orientation of these crystals, plus the mineral and chemical reactions that took place over millions of years formed all those unique kinds of granite that we see today. As a result of these processes granite is very hard, resistant to most house hold chemicals and often freeze/thaw stable.
Marble & Limestone
Marble and limestone are sedimentary stone. While granite forms deep within the earth and is pushed up towards the surface, sedimentary stones started at the surface and were pushed down. As the name implies, sedimentary stones were formed in places where layers of sediments were deposited, such as the bottoms of lakes, rivers and oceans. These successive layers are what give many marbles their gorgeous wavy veins. Marble and limestone are “Calcareous” stones, which means, these materials are mainly composed of calcium carbonate rocks. These rocks are sensitive to the mild acids typically found in your kitchen, so they are often recommended for indoor use like bathroom vanities, as parts of your furniture, or fireplace surrounds and mantels. As for the difference between marble and limestone? Marble simply has been under more heat and pressure for a longer period of time than limestone, which is why it can be polished to a high shine, whereas limestone will have a patina finish.
Travertine is another example of a calcareous stone. It is a kind of limestone that forms from a chemically unique sedimentary stone, creating many small holes in the body of the stone, allowing larger crystalline structures to grow. These holes are often filled in the processing of the slabs with cement or epoxy, giving travertine its unique look. Travertine, like marble and other limestones, is best used for indoor applications, away from the thermal shock caused by abrupt and large changes in temperature.
Metamorphic vs Magmatic and Sedimentary Stones
Sometimes, while forming in the ground, sedimentary and magmatic stones can be changed by additional as well as fluctuating heat and/or pressures. These changed stone are called “Metamorphic” stones. Some granites are metamorphic as well as magmatic, which is one of the reasons that there’s such a wide diversity of granites.
Soapstone is another example of a metamorphic rock. Soapstone is mainly composed of talc and magnesium that have been placed under great heat and pressure resulting it a dense but relatively soft stone. It’s this unique composition that gives this material a “soapy texture” and makes it resistant to the mild acids in your kitchen. Do note though, that unlike most stone products, soapstone is more easily scratched by kitchen utensils. However these fine scratches can be removed with a light sanding and then re-sealing of the stone.
Onyx is an example of a metamorphic, calcareous stone. The type of onyx used in counter or furniture applications is not the same as the gemstone onyx. This onyx is a banded calcite and is softer than “true onyx”. It is translucent and available in small slabs often for back-lit applications. Since it is a calcareous stone it is not resistant to mild acids.
Finally, there’s Quartzite, which is also a metamorphic stone. Quartzite is sandstone that has been put under tremendous tectonic pressure transforming it into quartz crystals and then cementing them together. While often composed mostly of the same siliceous stone like granite, quartzite can also include a blend of the calcareous stone like limestone and marble. Visually quartzite can have veining similar to many marbles or a beautiful almost transparent crystalline structure. As a result, not all quartzite is as acid-resistant as granite and this should be considered when deciding upon its application in your home.
Engineered Quartz is a man-made material subjected to rigorous fabrication processes that results in a product with very specific properties. This material is often easy to spot due to it’s uniform and consistent look.
Engineered Quartz products, sometimes just shortened to “quartz”, are a mix of quartz crystals and some silica, which are then blended with an epoxy resin, cast into a single block and cut into slabs. These quartz products are extremely hard, chemically-resistant, almost non-porous, and they are very consistent in their colourations. This process makes quartz products a very good choice for indoor applications like kitchens, bathrooms or furniture. You should note that Engineered Quartz products do not handle UV-light as well as Natural Stone products, so are they not recommended for exterior applications. Also because epoxy resins are used as the binder in the fabrication process these materials can be scorched if exposed to high heat.
Porcelain slabs are essentially very large porcelain tiles that have been manufactured to mimic the finish and feel of stone. Like Engineered Quartz, these products are very hard and extremely stain resistant. Unlike quartz slabs their thinness and light weight makes them uniquely suitable for creative applications such as backsplashes, shower walls and complete floor to ceiling fireplace surrounds. They can also be used for most counter applications. Unlike Engineered Quartz these Porcelain slabs are UV light-resistant, heat resistant and freeze/thaw stable so can be used outside.
Now that you know a little about how each stone is unique and what they’re best used for, you can start thinking about what kind of stone you want for your particular application. Of course, nothing beats speaking with a certified building professional or a properly trained sales individual prior to choosing your stone or “stone-like” product!
I hope this helps you on your journey with stone.
– Dennis Centis