Quartzite is a rock of metamorphic origin, meaning it formed through the transformation of one rock into another under the influence of external factors (temperature, pressure, and others).

Quartzite formed through the transformation of ancient quartz sandstones. Because of this, it typically has a uniform, fine-grained structure. Quartzite is a monomineral rock, meaning it consists essentially of a single mineral: quartz.

These two factors (mineral composition and fine-grained structure) determine the sum of the physical and mechanical properties of this stone. Due to its monomineral composition, the quartz grains that make up the rock expand uniformly when heated, without creating internal stress, making it resistant to fracture when used in a sauna.