Quartzite is a metamorphic rock formed when quartz-rich sandstone or chert has been exposed to high temperatures and pressures. Such conditions fuse the quartz grains together forming a dense, hard, equigranular rock. The name quartzite implies not only a high degree of induration (hardness), but also a high quartz content. Quartzite generally comprises greater than 90% percent quartz, and some examples, containing up to 99% quartz, and are the largest and purest concentrations of silica in the Earth’s crust. Although a quartz-rich sandstone or marbles can look similar to quartzite, they are not the same. Quartzite also tends to have a sugary appearance and glassy lustre. The variety of colors displayed by quartzite are a consequence of minor amounts of impurities being incorporated with the quartz during metamorphism. Although quartzite can sometimes appear superficially similar to marble, a piece of quartzite will not be able to be scratched by a metal blade, can scratch glass and will not fizz on contact with dilute hydrochloric acid.
Engineered stone (Quartz)
Quartz countertops are man-made engineered stone countertops formed by combining 90% ground quartz (a natural hard mineral) with 8-10% resins, polymers, and pigments. This forms a very hard granite-like surface. The appearance depends on how the quartz is ground: coarsely ground quartz produces a flecked appearance, while finely ground quartz produces a smooth look.
Pros: Extremely hard and durable; Available with a glossy sheen or a honed finish; non-porous and stain-and-crack resistant; does not require sealing or resealing; wide range of colors; easy to clean with mild soap, water, and a soft cloth.
Cons: Expensive; not heat tolerant; seams are inevitable for large countertop designs.