Is It Really Quartzite? How to Spot Mislabeled Stone
Published •6 min read
Quartzite is prized for looking like marble while being much harder and acid resistant. That popularity has a downside: the Natural Stone Institute warns that quartzite is commonly mislabeled, with marble, dolomitic marble and sandstone sometimes sold under the quartzite name. Because these stones behave very differently in a kitchen, it's worth testing a sample before you buy.
Why Mislabeling Matters
| Stone | Scratches glass? | Etches from lemon or vinegar? | Porosity |
|---|---|---|---|
| Real quartzite | Yes | No | Low to moderate, varies by stone |
| Marble or dolomitic marble | No | Yes (dolomitic etches more slowly) | Varies |
| Sandstone | Yes | No | Can be more porous; more prone to staining |
The Natural Stone Institute notes there's no such thing as "soft quartzite". A stone sold that way is most likely marble. It also notes that Super White is most commonly a dolomitic marble, and that Fantasy Brown has layers of both marble and quartzite and is best treated as marble.
Test 1: The Glass Test
- 1Get a glass tile and a sample with a rough, pointed edge.
- 2Lay the glass on a table and press the stone hard across it.
- 3Check the result: real quartzite scratches glass easily, and you'll hear and feel it bite. Non-quartzite leaves no scratch or a faint one, often just a powdery trail that rubs off.
- 4If the stone has different colors or minerals, test several spots.
No rough edge? Use a knife tip on the surface instead. Real quartzite is scratched lightly or not at all; marble scratches easily.
Test 2: The Etch Test
Put a little lemon juice or vinegar on the polished surface, leave it for about 15 minutes, then wipe it off. Look at a low angle. Etching can look lighter, darker or simply dull. Real quartzite shows no etching from everyday kitchen acids; marble shows obvious etching and dolomitic marble subtler etching. Strong acids, such as some rust removers, can affect even quartzite, so this test uses ordinary kitchen acids only.
Test 3: The Water (Porosity) Test
To tell quartzite from sandstone, the Natural Stone Institute suggests checking porosity: see whether the stone soaks up water. A magnifier also helps: sandstone shows individual sand grains, while highly metamorphosed quartzite has a glassy, crystalline surface. More porous stones aren't unusable, but they need sealing and more care.
What Doesn't Tell You
According to the Natural Stone Institute, the country of origin, the price and the name on the tag aren't reliable ways to tell quartzite from other stones, and marble and quartzite can look nearly identical. Testing is the only reliable way.
Tips for Testing
- Test an offcut or sample, not your finished countertop; marks can be permanent.
- Ask your supplier or fabricator if they've tested the stone.
- Test more than one area on stones with mixed colors.
Frequently Asked Questions
How can I tell if quartzite is real?
Real quartzite scratches glass and shows no change after about 15 minutes under lemon juice or vinegar. Marble fails both tests.
What is soft quartzite?
There's no such thing as soft quartzite, according to the Natural Stone Institute. A stone sold that way is most likely marble or dolomitic marble.
Is Super White a quartzite?
The Natural Stone Institute says Super White is most commonly a dolomitic marble, which means it etches from acids and won't scratch glass. Test the specific slab.
Can sandstone be sold as quartzite?
Yes. Sandstone is made of the same mineral and is just as hard, but it can be more porous. A water test and a close look at the texture help tell them apart.
Choosing Quartzite? Get a Quote from Mega Solutions
Mega Solutions installs quartzite, granite, quartz and marble countertops, and also sells and installs cabinets. Request a personalized quote based on your measurements and the stones you're considering.
Sources
- Natural Stone Institute, "The Definitive Guide to Quartzite": usenaturalstone.org
- Natural Stone Institute, "A Deep Dive Into the Properties of Quartzite": usenaturalstone.org
- Natural Stone Institute, "Natural Quartzite and Engineered Quartz: What's the Difference?": usenaturalstone.org
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