Quartzite

Hardness: 7 (Mohs scale), Color: Reddish-brown due to iron oxide staining, Luster: Vitreous to dull, Crystal structure: Granular/Microcrystalline, Cleavage: None (conchoidal fracture), Specific Gravity: 2.6-2.7

Formed from the metamorphism of quartz-rich sandstone. High heat and pressure cause the quartz grains to recrystallize and fuse together, forming a dense, interlocking network of crystals. It is found in mountain belts globally, often dating back hundreds of millions of years.

Commonly used as a decorative stone in landscaping, crushed stone for road construction and railway ballast, and occasionally used in countertop manufacturing or as a building material due to its extreme durability.

Quartzite is so hard that it will scratch glass and even steel. It is frequently more durable than the parent sandstone from which it originated, making it highly resistant to chemical and physical weathering.

Identify in the field by its superior hardness (cannot be scratched by a knife) and its grainy, sugary appearance on fresh surfaces. Unlike sandstone, quartzite breaks through the grains rather than around them. Found frequently in glacial deposits or mountainous regions.