Hey everyone, and welcome to my little corner of the web—where I get to talk about the stuff I’ve been obsessing over for the last decade as a Quartz supplier. If you’ve ever picked up a countertop, a watch face, or even that random rock you found on a hike and thought, “Wait, why is this so tough?” then you’re in the right spot. Today we’re diving into something I get asked literally every single week: what is the hardness of quartz anyway? And for the record, this isn’t just some random rock fact—it matters so much when you’re picking quartz for your project, whether it’s a kitchen redo or a custom tile job. Quartz
First off, let’s cut through the noise. I know a lot of people have heard of the Mohs scale, right? That 1-to-10 scratch test thing? Yeah, that’s the main one we use for minerals, and quartz sits dead at a 7 on Mohs Hardness Scale. But wait—don’t just take that number at face value. Let’s break this down like I’m explaining it to a customer who called me panicking because a can opener scratched their old quartz countertop. Because that’s basically my daily life.
Here’s how the Mohs scale works, super simple: it’s a relative scale, not absolute. So a 7 is harder than a 6 (which is feldspar, common in granite), softer than an 8 (topaz), way softer than a 9 (corundum, like rubies and sapphires), and way softer than a 10 (diamond). But the big mistake people make is thinking that a 7 means “unscratchable.” Nope. The Mohs scale is just about which minerals can scratch which others. So if you take a piece of quartz (7) and rub it against another 7, they’ll both scratch each other a little. If you rub quartz against something softer than 7—like calcite (3) or even your kitchen knife steel (which is around 5.5), that thing will scratch the quartz, not the other way around. That’s the whole point. And for what it’s worth, when I hear someone say “my quartz got scratched by a knife,” I don’t panic—most steels are only 5-5.5, so that makes total sense. We always tell customers not to cut directly on quartz, even though it’s 7, because even hard stuff can show marks if you’re reckless.
But wait—hardness isn’t just scratch resistance, right? As a quartz supplier, I see a lot of customers mix up hardness with durability, and that’s a huge misconception. Hardness is about how well a material resists scratching. Durability is a whole other bag—it’s about impact resistance, heat resistance, stain resistance, all that good stuff. For example, quartz is a super dense, non-porous material we make in our facility by mixing ground quartz (the mineral, 90-93% of the slab) with resin, pigments, and other binders. So that resin part? It’s softer than quartz, right? Resin is around 2-3 on Mohs, so the only reason the whole slab is a 7 is because of all that embedded quartz crystal. But that resin is what gives quartz its flexibility, so a drop of a heavy pan (like a cast iron skillet) is way less likely to chip than, say, natural granite, which is softer but more brittle. That’s the tradeoff we walk through with every client. I once had a architect client come in insisting their project needed “the hardest quartz ever” and we had to explain that a 7 is actually one of the hardest common countertop materials—harder than granite (which is 6-7, depending on the feldspar content), harder than most marble (3-5), way harder than solid surface materials like Corian (which is like 2-3). So when someone says “hard,” quartz is top of the line for most everyday uses.
Another question I get all the time: does quartz hardness vary between different brands? Ugh, yes and no. Let’s be real—not all quartz is made equal. At our facility, we use high-purity natural quartz crystals, ground to a specific particle size, mixed with UV-stabilized resin (so it doesn’t yellow) and no fillers that would lower the hardness. Some cheaper brands? They add more resin, more fillers, use lower quality quartz, and their slabs end up around 6.5 on Mohs. That’s a small difference, but it adds up. If you’re installing quartz in a commercial kitchen where they’re dragging heavy pots around and using metal utensils, a 6.5 slab will scratch way faster than a 7. I’ve had customers come to us after installing a cheap quartz from a big box store a year ago, and now it’s covered in scratches—they thought all quartz was the same hardness, which is so not true. So when we’re chatting about a project, I always pull out a little scratch test kit I keep in my truck (don’t judge) to show them: I take a piece of our 7 hardness quartz, a cheap competitor’s slab, and a piece of feldspar (Mohs 6). I rub them all on each other—our quartz scratches the feldspar, the cheap competitor’s scratches too, but the competitor’s slab gets scratched by the feldspar. That’s worth its weight in gold for customers who can’t tell the difference between a good slab and a cheap one just by looking at it.
Also, let’s talk about real-world testing, not just lab numbers. I’ve been in the industry for 12 years, so I’ve seen thousands of quartz slabs get put through their paces. We installed a big commercial kitchen at a coffee chain in downtown Chicago two years ago, and those countertops get hit with everything: dropped metal espresso machines, sharp barista tools, acid from coffee and citrus, hot steam. A year later, we went back to inspect—only a tiny, almost unnoticeable scratch in one spot where a barista dropped a 10-pound metal milk frother. That’s the hardness at work. Compare that to the marble they used in a café down the street—last year they had to refinish all the countertops because of scratch marks from sugar shakers and knife cuts. It’s not that marble is bad, it’s just way softer.
Wait, but what about myths? I hear so many people say “quartz is harder than steel” or “it’s almost as hard as diamond.” No, that’s not true. Diamond is 10, quartz is 7. Big gap. Steel is usually around 5-5.5, so quartz is harder than most steel, which is why you can’t scratch quartz with a knife if you do it light. But if you press hard, or drag a knife back and forth, you will get a mark. That’s not a flaw in the quartz, that’s basic physics. I always use the example of a diamond: you can scratch glass with a diamond, but if you drop a diamond on concrete, it’ll chip or even crack. Hardness isn’t everything. Same with quartz—its hardness makes it scratch-resistant, but the resin binder makes it flexible, so it doesn’t crack if you drop a pan, unlike glass (which is like 5.5, harder than some steels but super brittle).
Another thing I love talking about as a supplier: how quartz’s hardness makes it perfect for all kinds of projects, not just kitchens. We make quartz tiles for bathroom showers, and those get scrubbed with harsh cleaning products, brushes, even pumice stones sometimes. A 7 hardness quartz will hold up way better than a porcelain tile (which is around 6-7, but more porous if it’s not glazed) or natural stone (which is softer). We’ve had a hotel client use our quartz for their lobby floor, and after three years of foot traffic, roller bags, and furniture moving, there’s barely a scratch. That’s the hardness doing its job.
Now, let’s get to the part that actually matters: why does this matter for you? If you’re a homeowner picking quartz for your kitchen, you don’t need a PhD in mineralogy. But knowing that quartz is a 7 on Mohs, that that’s harder than granite, marble, and most solid surface, and that higher quality quartz is closer to a true 7 will help you make a better choice. If you’re a contractor, that knowledge will help you recommend the right product for the job—like, don’t suggest a low-hardness quartz for a commercial space, because it’ll wear out fast. If you’re just a curious person (hi, that’s most of my customers), now you have a fun fact to drop at your next dinner party: quartz is 7 on the Mohs scale, harder than a knife, softer than a topaz.
I should also mention that even with all that hardness, quartz isn’t indestructible. You can still scratch it if you drag a diamond-tipped drill bit across it (duh, that’s how they cut quartz for countertops) or if you slide a piece of metal with sharp, hard edges across it with a lot of pressure. We always tell customers to use cutting boards, trivets for hot pans, and wipe up spills—common sense stuff that protects any countertop, even the hardest one. Hardness doesn’t mean “invincible.” It just means it’s way more resistant to scratches than most other materials you’d use for surfaces.
As someone who’s in the thick of this every day, I’ve seen the confusion around quartz hardness so much. New customers come in, look at samples, and ask “why is this one more expensive than that other one?” A big part of that is the quality of the quartz crystals. We source our quartz from mines in the US and Brazil that produce high-purity, consistent crystals, so our slabs have that true 7 hardness. A lot of budget brands use lower-grade quartz, more resin, and their slabs are softer, so they have to charge less, but they don’t last as long. We’ve had customers switch to our product after going through two sets of cheap quartz in five years—they say it’s worth every penny because it doesn’t scratch, it doesn’t yellow, and it looks good for decades.
So to wrap this up: the hardness of quartz is 7 on the Mohs Hardness Scale. That number is relative, not absolute, meaning it’s harder than most common minerals and surface materials, but not unscratchable. The hardness comes from the natural quartz crystals in the slab, mixed with resin binders that give quartz its durability and flexibility. Not all quartz is the same—higher quality slabs will hit that true 7, while cheaper ones can dip to 6.5 or lower, which affects how well they hold up to daily use. And most importantly, that 7 hardness makes quartz one of the best all-around surface materials for kitchens, bathrooms, floors, and more, balancing scratch resistance with durability.
If you’re thinking about quartz for your next project—whether it’s a small bathroom remodel, a big commercial build, or something in between—I’d love to chat. I’ve been doing this long enough to help you pick the right slab, explain all the technical stuff in plain English, and make sure you get exactly what you need. Don’t hesitate to reach out and start the conversation. I’m here to help, not just sell quartz.
Brown Marble References:
- Nesse, W. D. (2013). Introduction to Mineralogy. Oxford University Press.
- Mohs, F. (1822). Versuch einer Elementar-Methode zur naturhistorischen Bestimmung und Erkennung der Fossilien. Leopold Sommer.
- Quartz Manufacturers Association. (2021). Global Quartz Surface Industry Report.
- Klein, C., & Dutrow, B. (2020). Manual of Mineral Science (23rd ed.). Wiley.
Xiamen Yigong Import and Export Co., Ltd.
As one of the most professional quartz suppliers in China, we also support customized service. With abundant experience, we warmly welcome you to buy high quality quartz for sale here from our factory. For price consultation, contact us.
Address: No.850-2 Xingxi Road, Houxi Town, Jimei District, Xiamen
E-mail: ella@xmyigong.com
WebSite: https://www.yigongstone.com/
