In many cases, it’s not even possible to tell marble and quartzite apart visually. The country of origin, price, or the name of a stone are not reliable indicators of what type of rock you’ve got. Things that do not help distinguish quartzite from non-quartzite White Macaubas and Calacatta Macaubas have been exposed to less intense pressure, so they are more porous and will benefit from sealing. Some, like Taj Mahal or Sea Pearl, have been highly metamorphosed, and the minerals are bonded together tightly. But quartzite will not etch at all from normal kitchen acids. Dolomitic marble etches slightly more slowly than regular marble. Marble and dolomitic marble, on the other hand, will etch from these acids. If a rock labelled as quartzite becomes etched from acid, then it’s been mislabeled. Quartzite will not etch from acids like lemon juice or vinegar. A rock labelled as soft quartzite is most likely marble. There is only one kind of quartzite and it’s hard. There is no such thing as soft quartzite though. The unfortunate term “soft quartzite” has emerged to try to explain why a rock that is labelled quartzite is actually not hard and durable like real quartzite. If a rock that is labelled as quartzite is soft, then it was mislabeled. These things are easy to test with a sample of stone. That means it’s harder than glass and harder than a knife blade. Not only does this make for a tough stone, but it also makes it easy to tell quartzite from the imposters. You needn’t be a geologist to appreciate the hardness and durability of quartzite. (Note I’m talking about the mineral quartz, not the composite countertop material that is also named quartz.) Properties of quartzite That’s helpful because quartz has distinct properties that make it easy to tell apart from other minerals. Regardless of colour, quartzite is made of one thing: quartz. ![]() Van Gogh and Azul Macaubas quartzites are examples of vivid colouring. Additional minerals carried by groundwater can impart hues of green, blue, or ion-red. Quartzite is usually white or light-coloured because quartz sand is light coloured. The process is similar to individual snowflakes merging into solid, glacial ice. With enough heat and pressure, the sand grains lose their original shape and fuse to their neighbours, forming a dense, durable rock. If the sandstone gets buried ever more deeply underneath layers of rocks, it gets hotter and more compressed. Over time, the sand grains become compressed and stuck together to form sandstone. Quartzite begins its geologic life as sand grains, perhaps on a beach, desert dune, or riverbed. Quartzite is a metamorphic rock made almost entirely of the mineral quartz. Unfortunately, it has variable labelling.Įmerald Green Quartzite at VSG. But it isn’t quartzite has very consistent properties. ![]() Because each of these stones behaves differently, people might understandably conclude that quartzite is variable. Some quartzite is the real deal, but sometimes marble or dolomitic marble are labelled as quartzite. I’ll get right to the point: quartzite is commonly mislabeled. Let’s use my favourite tool – geology – to suss out the answer to this mystery. ![]() Which is it? Why are there such conflicting reports about quartzite? Yet, others report that it’s harder than granite. Sometimes you hear it’s a hybrid between marble and granite. A quick internet search will reveal an unsettling disparity of information. Quartzite may be the most confusing natural stone out there. Read the full article, The Definitive Guide to Quartzites by Karin Kirk here. It answers a lot of commonly asked questions about one of our favourite Brazilian stones. Here’s a great article we found on a Guide to Quartzites. Use Natural Stone is a great online resource for learning everything natural stone.
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