I think that a good question to start off with today is,
What is natural stone?
I like Marco Campagna’s definition as stated in Studio Marmo, Stone Sampler:
“A portion of rock used as building or decorative material.”
Now that sounds simple enough, a little broad maybe but essentially a good straight-forward definition. If anyone should understand a definition like that it would be those of us who live here in northern Ontario. I mean, let’s face it we live in the Canadian Shield, we are surrounded by stone, or should I say we are surrounded by rock because not all rock can be used as a decorative or building material, and not all natural stone can be used for all applications.
Let’s face it, when it comes to construction most of us in North America come from a wood culture. I’m sure if I asked most you what Birch or Maple or Oak was you would, at the very least know that these are woods. Some of you might even be able to pick out these woods looking at samples in a cabinet shop and few more would know that each of those woods were different when it came to how hard or tough each was in comparison to the other.
Now, if I asked you about UbaTuba or Monaco Brown for example, would you know one was a granite and the other was a marble? Or that one could be etched by a mild acid while the other was impervious to it? Would you then say that Monaco Brown is wonderful stone to highlight a cream or ivory sink in your bathroom and UbaTuba is one of the denser granites and would make a great outdoor kitchen counter? Probably not. So today I’ll try to give you some information about the differences and qualities of marble, limestone, travertine and granite. I will also try to touch briefly on soapstone and engineered quartz.
Geologically speaking and I’ll keep this to a minimum, stone is divided into 3 groups:
Magmatic (Magma – Lava, this starts off very hot cools and becomes very hard – Granite is an example.)
Sedimentary (bottoms of rivers, lakes, oceans etc. and over time the deposits because of pressure form into rock – Limestone, Sandstone, Travertine.)
Metamorphic (all the above changed by heat and pressure – Marble, some Granites and Soapstone.)
All of the stones that we use in the counter top industry were formed millions of years ago. Some hundreds of millions of years ago. I often get questions like, I really like the look of UbaTuba can I order it in a lighter shade. Sorry, it was all made about 450 million years ago but if you have lots of time you can always try to put an order in now and wait it out.
So what stone should you use for you kitchen or vanity?
Marbles and most sedimentary stones like limestone are composed of carbonites and as a result they react with acids. So lemon juice, vinegar, wine, all contain acetic acid and they will react with those stones. So typically we wouldn’t recommend these types of stones for kitchens. Bathroom vanities, furniture and fireplaces, those are the real homes for marbles and limestones. As well these stones are not the best for outdoor use because they tend to be somewhat absorptive and therefore they can fail or crack after a number of freezes and thaws.
Granite is composed of feldspars, silicas and quartz. These crystals are very hard and do not react with mild acids. Soapstone is mainly composed of talc and some magnesium and as well doesn’t react much with mild acids. Engineered quartz stone is composed of silica and quartz, also non-reactive with mild acids. So granite, soapstone and engineered quartz stone all work well in kitchen environments.
Outdoor applications, especially in our neck of the woods (the land of ice and snow), should be the domain of granite that was magmatic in origin only. The continual exposure to UV light makes engineered stone not so good and metamorphic granites may have too many fissures allowing water to penetrate the stone and cause a failure or cracking over successive freeze thaw cycles.
So how can you tell these stones apart without being a geologist? Sometimes it’s not so easy but here are a few hints.
Marble and limestone are composed of very fine crystals. Much finer than most granites and travertines. The difference between marble and limestone is that marble is harder and therefore will polish nicely. Limestone is actually the precursor of marble. All marble was once limestone but because of heat and pressure was changed into marble. So because it’s not as hard as marble limestone will not have a high polish finish but more of a patina finish.
Travertine is formed like limestone. It has a similar hardness but is chemically a little different and as a result is full of holes which are usually filled with a cement or epoxy after it has been cut into tile or slabs. Typically travertine has a larger crystalline structure than limestone and marble but the holes really give it away.
Granites have a very strong, large crystalline look. They can be veined or non-veined and some have a breccia appearance which means they look like a bunch of stones that were squashed together because they were, over a very long period of time. The veins can be orientated or non-orientated, not a big deal but important when you consider the layout of the stone on your counter.
Engineered quartz is exactly what it sounds like. An engineer took a pile of quartz crystals and some silica, mixed it with an epoxy resin, cast the whole lot into a block and when it hardened cut it into slabs and polished them. As a result you have a very hard product, a more uniform granite look with slabs that are all the same size and colours that are very consistent. Very good for kitchen and baths, not so good outside because the UV may affect the colour of the material over time.
So that was a quick and simple look at stone. Hope it helps.