Quartzite (River Cobble)

Hardness: 7 (Mohs scale), Color: Brownish-tan due to iron staining, Luster: Vitreous to dull, Crystal Structure: Granular/Microcrystalline, Specific Gravity: 2.6-2.7

Formed through the metamorphism of quartz sandstone under intense heat and pressure. This specific piece shows significant rounding, indicating it was transported by water over a long period, likely in a riverbed or glacial deposit.

Used widely in construction as decorative stone, railway ballast, and road aggregate. Highly durable and resistant to chemical weathering.

Quartzite is so tough that it often survives multiple cycles of the rock cycle; as it breaks down, it creates quartz sand which can then reform into sandstone and quartzite again.

Identify by its extreme hardness (cannot be scratched by a steel knife) and granular sugary appearance on fresh surfaces. Often found in riverbeds, glacial tills, or mountain ridges.