Quartzite is a natural stone. It is a metamorphic rock, meaning it formed entirely through the Earth’s natural geological processes. The frequent confusion arises because of the similar name to “engineered quartz,” which is a man-made product. Understanding the difference between these two materials requires looking closely at their origins, composition, and resulting physical properties. Quartzite is quarried directly from the earth as a solid stone.
The Geological Identity of Quartzite
Quartzite begins its formation as pure quartz sandstone, a sedimentary rock composed primarily of quartz grains. Over millions of years, this sandstone becomes buried deep within the Earth’s crust and subjected to intense heat and immense pressure.
This process, known as metamorphism, causes the individual quartz grains to lose their original boundaries and fuse together. The result is a dense, interlocking network of quartz crystals that are structurally stronger than the original sandstone.
The primary mineral composition of quartzite is silica, or quartz, often making up 90% to 99% of the rock’s volume. The interlocking crystal structure gives quartzite its characteristic hardness and durability. While pure quartzite is typically white or light-colored, the presence of trace minerals like iron oxide can introduce natural hues of pink, red, yellow, or blue.
Distinguishing Quartzite from Engineered Quartz
The similarity in names often leads to the mistaken belief that quartzite and engineered quartz are the same material, but their origins are fundamentally different. Natural quartzite is a 100% mineral product of geology, while engineered quartz is a manufactured composite material. The production of engineered quartz takes place in a factory.
Engineered quartz typically consists of 90% to 95% crushed natural quartz aggregates mixed with a binding agent, usually a polymer resin, making up the remaining 5% to 10%. Pigments are also added to achieve consistent color and pattern.
The presence of polymer resins is the most significant difference from natural quartzite. This resin allows for non-porous, consistent slabs but also makes the material susceptible to damage from prolonged exposure to ultraviolet (UV) light, which can cause yellowing over time. Natural quartzite, lacking these resins, is stable under UV light and is suitable for both indoor and outdoor applications.
Manufacturing also affects heat tolerance. While natural quartzite can withstand very high temperatures due to its formation, the resin in engineered quartz can melt or scorch when exposed to high heat sources.
Key Physical Characteristics and Practical Use
Quartzite’s natural formation under pressure results in superior physical properties, making it valued for practical applications like countertops and flooring. The hardness of natural quartzite is a defining characteristic, often scoring 7 on the Mohs scale of mineral hardness. This level of hardness makes it highly resistant to scratching, even surpassing materials like granite.
This density also contributes to its heat resistance; because it is a pure mineral stone, it can tolerate high temperatures without degradation or scorching. While it is generally heat-stable, using a trivet is advisable to prevent thermal shock. The average density of quartzite is approximately 2.7 grams per cubic centimeter, which contributes to its overall durability.
The porosity of quartzite is variable, depending on the extent of its metamorphism. Varieties that have been fully metamorphosed have very low porosity, while others may be slightly more porous, requiring periodic sealing to prevent staining. Sealing helps to fill any microscopic voids, enhancing the stone’s resistance to liquids and oils. Real quartzite will not etch when exposed to common kitchen acids like lemon juice or vinegar.