Q&A: Why is granite more scratch resistant than marble or soapstone?

To answer this question, we need to have a little geology lesson. But wait, don’t run away! We’ll keep things simple, and we think you’ll find it fascinating to know a bit more about that awesome stone you have or might put in your house.

Mohs Scale of Hardness

Granite, marble, limestone, even engineered quartz products all contain various natural minerals. Stones are classified based on which minerals are in the rocks, as well as how the rocks were formed. See these other blog posts for more information on marble and granite specifically. In this post, we’ll be talking about the minerals.

Now, scientists classify mineral hardness using various methods, but the most common by far is called Mohs Scale of Hardness.

Mohs scale of hardness was developed by a German mineralogist named Friedrich Mohs. It rates the hardness of a mineral from 1 to 10, and rather than give each number a definition like “soft” and “hard”, Mohs used a mineral to define each number. Talc is the softest (#1), and Diamond is the hardest, (#10).

The way the scale works, any mineral can scratch any other mineral with a number on Mohs scale below it. Quartz (#7) can scratch all minerals numbered 1-6 (feldspar and calcite, for example). Diamonds (#10) can scratch anything.

Quartz CrystalSo, why is this information interesting and useful? Well, knowing a bit about what minerals are most often in different stones can tell us a lot about how they’ll behave. Soapstone, for example, contains a lot of talc, while granite contains a lot of quartz. So, common sense sells us then that granite is likely much more resistant to scratching than soapstone because it’s harder. And that’s correct!

Marble, and limestone too for that matter, has a lot of calcite which is a #3 on the scale. So marble is harder than soapstone, but softer than granite.

Quartz, a manmade material which contains about 93% quartz, is harder than some granites. Granites contain mostly quartz (#7) and feldspars (#6). However, they get a lot of their colors from other minerals which may be softer. If a particular granite has a lot of softer minerals in it, it will overall be less scratch resistant than an engineered quartz product.

In general, the softest stone we generally use in homes is soapstone. (It’s also one of the easiest to repair as you can generally simply buff out scratches, see our page here). Second up is marble, followed by granite and quartz which both provide very durable, scratch resistant, stain resistant, easy care surfaces for your home.

See, that wasn’t too bad was it? And now you know a bit of geology!

Have another question? Let us know in the comments below!

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