What Is Quartzite?
Quartzite is a metamorphic rock formed basically by mineral quartz, that starts in the form of grains and sand like the ones in dunes and riverbeds, which, as time goes by, are compressed until they form sandstones. However, if buried deeper under layers of rocks and associated with an increase in temperature and pressure, they lose their original shape and merge with the ones near them, forming a dense and durable rock. Normally, these rocks have light tones, with the possibility of changing to other colours due to additional minerals carried by the groundwater, transferring tones such as green, blue, and red. Among the stones for coverings, the hardness of quartzites is the highest, because they have more than 75% of quartz in their composition, reaching in some cases more than 90% of quartz, like Perla Santana, which has got 94% in its composition.
This makes quartzites harder than glass or than a knife blade, which can easily be tested when trying to scratch the stone with one of these elements. Besides, they are materials with very low porosity and absorption when “crystalline”, which indicates a very high degree of metamorphism, that is, when the sandstone — protolith, the rock that preceded the metamorphism and which generated the quartzite — suffered the highest temperatures and compressions, reaching 800ºC. Not to mention the crystals that, in the beginning, were sand and ended up merging and forming this super stone, Perla Santana, a true quartzite. Another element that evidences a quartzite is the non-reaction of the stone to the exposure to acids. Marbles, on the other hand, no matter the type, react to these elements. It is worth mentioning that almost everything people manipulate in a kitchen has acidic substances in its composition, like tomatoes, lemons, or even olive oil and wines. Attention to this matter: in nature, there is a group of rocks called meta sandstones, which are nothing more than sandstones that have also undergone metamorphisms, however, of low degree or intensity.
What evidences this is the low cohesion among the crystals, causing these rocks to have from moderate to very high absorption. These are stones that do not react to acids, with high hardness levels, and that are formed from the same quartz as quartzites. However, their formation is “somewhere in between”, which is didactically illustrated in the following pictures. Quartzites are the great revolution in the area of ornamental stones. Their appearance in nature dates back to 600 million years. However, because of its high hardness and extremely fragile structure when in nature — due to fractures suffered in its formation process that go up to extreme levels —, it took a revolution in the industry and mining so that the stone could be mined and processed. The diamond wire saw, which emerged in Italy in the 1970s, arrived in Brazil in the 1990s and got into the industries at the end of the same period, reached its peak only in mid-2010 when quartzites could be extracted from nature and processed in the industry. They are unique stones that add value to any project, as they have a classic beauty like the noblest marbles, with the maximum resistance that only they have in nature in amounts and conditions of use for coatings.