Natural Quartzites 101
Ben Cole
Stone Industry Consultant
Over the past several years natural quartzites have skyrocketed in popularity in the residential sector of the stone counter tops business.
But with new stones coming on the market all the time, many of them being labeled quartzites by ill-informed importers, quartzites are getting a bad rap and fabricators and homeowners are being misled. To understand this issue it is important that importers and fabricators educate themselves and the customers they serve.
So exactly what is quartzite and how does it differ from marble and granite? Quartzite is a metamorphic stone that is formed under extreme heat and pressure caused by tectonic forces. It is composed of roughly 90% to 99% quartz, a clear crystalline mineral, but most of the stones contain some impurities or other minerals that give the quartzites their color.
Quartz is one of the hardest minerals on the planet, and measures an 8 on the Mohs scale. To give you some perspective on how hard this is, the Mohs scale measures from 1 to 10, with ten being diamond, or the hardest mineral on earth. Quartzite’s extreme hardness makes it nearly impossible to scratch and most quartzites are very stain resistant.
Over the past several years, new technologies have made it commercially viable to mine quartzite slabs for the stone industry. And as many consumers are discovering they can now get the look of marble with a natural product that offers even better durability than granite, the demand for quartzite has risen exponentially. But with this growing popularity, many importers have been quick to label new stones as quartzites to cash in on the demand and help move their products. Unfortunately, many of the stones being labeled quartzites are not actually quartzites at all.
A great example of a mislabeled stone is the wildly popular White Fantasy (also often called Super White). The White Fantasy is actually a dolomite. It is denser and harder than marble but is not even as hard as a standard granite, let alone quartzite. The White Fantasy scratches less easily than a marble but more easily than a granite. It does contain low levels of calcium which make is susceptible to acid etching, however, I have found with a good sealer that the White Fantasy is much less susceptible to acid etching than a marble.
Another popular stone being mischaracterized as a quartzite is the stone (quarried in India) Brown Fantasy. This material is actually a hard marble, and far from a true quartzite.
In today’s competitive market fabricators need to be wary of any new stones coming on the market that are being sold as a quartzite. It is important to ask the importer questions to ensure they are familiar with the stone and are sure what category the stone falls under.
I also suggest getting a sample of the stone and running a few basic tests. If you run a knife across the surface of a quartzite or granite it should not scratch the stone. This is not the case with marble, which is softer than steel on the Mohs scale and will scratch. Place some citrus juice on top of the sample and leave it on overnight. If the stone etches, it contains calcium and is likely a marble and not a true quartzite.
Awareness of the type of stone and its properties can also help in estimating the true cost to fabricate the material.
Marble often requires more time refinishing faces and the call back percentages are much higher for jobs where another trade may have scratched the top or a coffee spill was left on for a prolonged period of time and caused etching within the first few weeks the of the tops being installed. Although quartzites may not have acid etching and scratching issues, the extreme hardness of the material causes much faster tool wear.
Blades that may last a month cutting granite on a daily basis can wear out twice as fast when working on quartzites. The same applies for router bits, especially the fancier edge shapes, as those bits not only have a high cost but lose shape much more quickly when working on the hard quartzites.
Make sure you are aware of the properties of the stone you are working with and make sure to educate your customer to avoid unrealistic expectations, future headaches, and under bidding jobs. Also, a customer will respect your honesty and you will avoid the threat of damaging your most important asset: your reputation.
Ben Cole grew up in the stone industry working in his family’s shop and currently manages a family-owned fabrication shop in southern New Jersey.