This is not to be confused with Quartz, the man-made engineered stone formed by combining 90% ground quartz with 8-10% resins, polymers, and pigments.
Hopefully I’ll be able to answer any questions you’ve had about this popular stone.
Is quartzite a hybrid between marble and granite?
Quartzite is a metamorphic rock made almost entirely of the mineral quartz. Quartzite begins it’s life as a quartz-rich sandstone. If the sandstone gets buried deeply underneath layers of rocks, through the pressure and heating that results from tectonic compression the sandstone transforms into quartzite gradually and with little change at a mineralogic level.
Is all Quartzite white?
Quartzite is usually white or light-colored because quartz sand is light colored. Additional mineral impurities carried by groundwater can impart hues of green, blue, or ion-red.
How Hard is Quartzite?
One of the appeals of quartzite is its hardness and durability. Quartz is 7 on Mohs hardness scale. To put this into perspective, your fingernail is 3 and it can scratch softer Calcite and Limestone. Knowing this can be helpful in spotting impostors.
Too many people are being sold marble thinking it is a premium quartzite. Using a rough section or pointy edge, real quartzite will scratch the glass tile. Non-quartzite will either leave no scratch or a very faint scratch.
You can do a similar test with a knife blade. Try to scratch the rock with the tip of the blade. Genuine quartzite will be scratched lightly or not at all. Marble or dolomitic marble will be easily gouged.
If you don’t have these results with your sample of quartzite, don’t believe the salesperson – no matter how convincing he seems to be.
Note: A few geologists use the word “quartzite” for sedimentary rocks that have an exceptionally high quartz content. This usage is falling out of favor but remains in older publications. The name “quartz arenite” is a more appropriate and less confusing name for these rocks.
Will Quartzite etch like marble?
True quartzite will not etch from kitchen acids. One of the appeals of quartzite is that it does not etch from acids like lemon juice or vinegar. If a rock labeled as quartzite becomes etched from acid, then it is mislabeled.
Is Quartzite porous?
Quartzite has a range of porosities. Some, like Taj Mahal or Sea Pearl, have been highly metamorphosed, and the minerals are bonded together tightly. White Macaubas and Calacatta Macaubas have been exposed to less intense pressure, so they are more porous and will benefit from sealing.
What is Soft Quartzite?
There is no such thing as soft quartzite. Stones labeled as soft quartzite are most likely marble. For instance, Super White is one of the stones that is frequently confused with quartzite. It is dolomitic marble. That means it won’t
scratch glass and it will etch with acids. Dolomitic marble is slightly slower to etch than regular marble, which can lead people to think that the stone
won’t etch. But it will still etch.
The country of origin, price, or the name of a stone are not reliable indicators of what type of rock you’ve got. In many cases, it’s not even possible to tell marble and quartzite apart visually. That’s why the tests are so useful.
How do I care for my Quartzite?
Natural quartzite’s hardness protects it from scratching and etching, but as a natural stone, yearly coating with a penetrating sealer is recommended. Other than that, natural quartzite care is simple.
Quartzite’s non-porous surface makes it a great choice for any wet areas in the home such as bathroom counters, backsplashes and shower surrounds – and, of course, the kitchen’s focal point countertop.
Here I’ve used a remnant of Perla Venata in a master closet and laundry room remodel.