Quartzite pebble

Hardness: 7 (Mohs scale), Color: Creamy white to light tan, Luster: Vitreous to dull, Crystal structure: Hexagonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific gravity: 2.6-2.7

Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, typically during mountain-building events. This specific specimen appears to be water-worn, indicating a long secondary history of erosion in a river or coastal environment.

Commonly used as crushed stone in construction, railway ballast, and decorative landscaping. High-purity quartzite is used to produce glass and metallic silicon.

Quartzite is so tough that it often survives multiple cycles of erosion and deposition. It is harder than steel and can easily scratch a glass plate or a knife blade.

Identify by its extreme hardness and grainy, sugary texture visible under a hand lens. It lacks the flat, layering planes found in sandstone. Often found in glacial till or as river cobbles in mountainous regions.