Quartzite Cobble

Hardness: 7 (Mohs scale), Color: light grey to tan/brownish, Luster: vitreous to dull, Crystal structure: granular/microcrystalline quartz, Cleavage: none (breaks with conchoidal fracture), Specific gravity: 2.6-2.7

Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure. It often dates back to various geological eras depending on location, frequently found in ancient riverbeds as eroded cobbles.

Commonly used as high-quality construction aggregate, decorative landscaping stone, and historically served as a durable material for stone tools or 'hammerstones'.

Quartzite is so durable that it can survive billions of years of erosion; it is often harder than the mountain ranges from which it originated. This specific specimen shows 'chatter marks' indicative of transport in a high-energy water environment.

Identify in the field by its inability to be scratched by steel, its sugary grain texture when broken, and its rounded shape if found in river deposits. Look for it in high-grade metamorphic terrains or glacial deposits.