Red Quartzite

Hardness: 7 (Mohs scale), Color: Reddish-brown/pink, Luster: Vitreous/glassy, Crystal system: Hexagonal (trigonal), Cleavage: None/conchoidal fracture, Specific gravity: 2.6-2.7

Formed through the regional metamorphism of quartz-rich sandstone. High heat and pressure reciprocal to tectonic movements cause individual sand grains to recrystallize and fuse together, typically in precambrian to paleozoic mountain belts.

Commonly used as a decorative stone, in construction as crushed stone for road beds or railway ballast, and in landscaping. Polished stones like this are popular for rock tumbling and aquarium decor.

Quartzite is so tough that it often survives intense erosion to form the crests of ridges. It is often confused with marble, but unlike marble, it will not fizz with acid and is hard enough to scratch glass easily.

Identify in the field by its hardness (cannot be scratched by steel) and its granular, sugary texture. Look for it in high-grade metamorphic terrains or as rounded river cobbles in mountainous regions.