Quartzite

Hardness: 7 (Mohs), Color: brownish-tan with dark inclusions and white quartz veining, Luster: Dull/Waxy, Crystal Structure: Granular/Textured, Cleavage: None

Formed from the regional metamorphism of quartz-rich sandstone under intense heat and pressure, typically during tectonic plate collisions. This specimen shows significant weathering and iron oxide staining.

Commonly used as crushed stone for road construction, railroad ballast, and sometimes as dimension stone in architecture due to its extreme durability. Weathered specimens like this serve as river rock landscaping.

Quartzite is so hard that it can scratch a glass plate and is one of the most chemically and physically resistant rocks found on Earth's surface. It often outlasts the surrounding rocks due to erosion resistance.

Look for a granular texture that resembles sandstone but shares the extreme hardness of quartz. It will not react with acid. Commonly found in ancient mountain belts and riverbeds where harder stones aggregate.