Natural Quartzite and Engineered Quartz: What’s the Difference?

by | Dec 6, 2019 | Educate

Engineered quartz and natural quartzite are both popular choices for countertops, backsplashes, bathrooms, and more. Their names are similar, and are sometimes (incorrectly) used interchangeably. But even aside from the names, there’s a lot of confusion about these materials.

Here’s a quick and handy reference for understanding both engineered quartz and quartzite: where they come from, what they’re made of, and how they differ.

 

Quartzite is a natural stone.

Quartzite is 100% natural and comes directly from the earth. Quartzite has formed in locations all around the planet and the most well-known quartzite quarries are in Brazil. Quartzite is also quarried in the United States, Sweden, Canada, Norway, India, and Italy, among other locales. Dramatic settings like the Medicine Bow Mountains in Wyoming show off quartzite in its natural habitat, where an impressive massif of white quartzite rises above the surrounding terrain.

Medicine Bow Peak in Wyoming is made from white quartzite that is over a billion years old. Photo: Wikimedia Commons by Fredlyfish4.

 

Engineered quartz is manmade.

Even though the name “quartz” refers to a natural mineral, engineered quartz (sometimes also called “engineered stone”) is a manufactured product. It’s made from quartz particles bonded together with resin, pigments, and other ingredients. Manufactured quartz is made in factories in the United States, Europe, and Asia, among other locations.

 

Natural quartzite contains minerals, and nothing else.

All quartzites are made of 100% minerals, and are purely a product of nature. Quartz (the mineral) is the main ingredient in all quartzites, and some types of quartzite contain smaller amounts of other minerals that give the stone color and character. The diverse options in aesthetics are impressive—and all from the earth. So if you like calm monochrome, nature provides that. If wild streaks of color tug on your heart, nature’s got you covered.

Some examples:

 

Engineered quartz contains minerals, polyester, styrene, pigments, and tert-Butyl peroxybenzoate.

The exact blend of ingredients in engineered quartz varies by brand and color, and manufacturers tout the high percentage of minerals in their slabs. The oft-cited statistic is that manufactured quartz contains 93% mineral quartz. But there are two caveats. First, 93% is the maximum, and actual quartz content can be much lower. Secondly, that percentage is measured by weight, not volume. A particle of quartz weighs a lot more than a particle of resin. So if you want to know how much of a countertop surface is made of quartz, then you need to measure the ingredients by volume, not weight. Based on proportions of materials in PentalQuartz, for example, the product is around 74% mineral quartz when measured by volume, even though it’s 88% quartz by weight.

 

Quartzite is made from geologic processes, over millions of years.

Some people (me included!) love the idea of having a slice of geologic time in their home or office. Every natural stone is an expression of all of the time and events that shaped it. Each quartzite has its own life story, but many were deposited as beach sand, and then buried and compressed into solid rock to make sandstone. Then the stone was pushed deeper into Earth’s crust where it was further and compressed and heated into a metamorphic rock. During metamorphism, quartzite experiences temperatures somewhere between 800° and 3000° F, and pressures of at least 40,000 pounds per square inch (in metric units, that’s 400° to 1600° C and 300 MPa), all over the course of millions of years.

Natural quartzites are not all alike. There is variation in how deeply they were buried and for how long, and what types of conditions they endured. Because of this, some quartzites are somewhat porous (like Macaubus), while others are tightly bonded together (like Marine Blue, Taj Mahal, or Fusion). For an explanation of the different members of the quartzite family, check out A Deep Dive Into the Properties of Quartzite.

 

Engineered quartz is made in a mold.

Many quartz brands are made with the patented Breton process, which involves pouring the ingredients in slab-shaped molds, then subjecting the mixture to a vacuum, vibration, and pressure. In the words of the manufacturer, it’s called “compaction by vibrocompression vacuum process.” The Breton process compresses slabs at around 30 pounds per square inch, and applies heat up to 360° F for around 40 minutes (in metric, that’s 180° C and 0.2 MPa). For comparison, that’s about the same amount of pressure in a car tire, and the same temperature and duration as if baking a casserole. Then the slabs are cured in a kiln, cooled, and polished. Compared to nature’s way of making stone, this is certainly quicker and more controlled, but the amount of heat and pressure used to manufacture a slab are far less than what happens in nature.

Because quartz particles are encased in resin, engineered quartz ends up having low porosity even though it is not compressed as much as natural quartzite (water absorption up to 0.02% in weight, according to Breton). On the other hand, the presence of resin means that engineered quartz is softer than natural quartzite.

 

Quartzite can be used indoors and out.

Natural quartzite is at home in many applications, from countertops and flooring, to outdoor kitchens and cladding. Harsh weather and UV light won’t affect the stone.

 

Engineered stone is best left indoors.

As I learned when I left several quartz slabs outside for a few months, the resins in engineered stone will turn yellow in the sunlight.

 

Quartzite is often misunderstood.

An unfortunate side effect of the desirability of quartzite is the temptation to sell stones as quartzite when they are not quartzite. Thus, quartzite is commonly mislabeled, which has resulted in widespread confusion about the properties of the stone. So-called “soft quartzite” is usually marble, which has entirely different properties than real quartzite. Simple diagnostic tests can be used to differentiate quartzite and marble. Furthermore, some sandstones are sold as quartzite, which further adds to the mix-up. Sandstone and quartzite have the same mineral ingredients (quartz), but quartzite has much lower porosity, as is explained in the Deep Dive into the Properties of Quartzite. Thankfully, it seems that both industry pros and consumers are becoming more discerning about what quartzite truly is, or is not.

 

Engineered quartz is misunderstood, too.

One well-known brand of manufactured quartz literally calls itself natural stone, which it isn’t. Manufactured quartz is sometimes thought to be maintenance free, which would be nice, but engineered surfaces are not immune to staining, chipping, scratching, or damage from excessive heat. Just as with any other material, users of manufactured quartz surfaces need to be mindful of the properties of engineered quartz and the particular requirements for its care.

Some misconceptions about engineered quartz are addressed in Sifting Through the Confusion about Manmade Quartz Surfaces and Do Engineered Quartz Countertops Stain?

 

Quartzite needs sealing.

The most common problem with quartzites is inadequate sealing – particularly along the edges and cut surfaces. As described above, some quartzites are porous and care must be taken to seal the stone. When in doubt, be sure to work with a fabricator who is experienced with the particular quartzite you are considering.

 

Engineered quartz should be protected from heat and not scrubbed too hard.

In a series of tests, major brands of engineered quartz stood up reasonably well to staining, but were damaged by scrubbing with abrasive cleaners or scouring pads. Exposure to hot, dirty cookware damaged some types of quartz, as was shown in a performance comparison of countertop materials.

 

Which should you use?

There is no simple answer to this question. Each material has its devoted fans and selling points. No matter which surface you choose, be sure to obtain samples that you can test, work with a reputable dealer and fabricator, and take some time to learn about the product. While labels and misconceptions can cause confusion, the combination of informed customers and experienced professionals can help ensure that materials are used in ways that allow them to perform well, last a long time, and look terrific every day.

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