Quartzite

Hardness: 7 (Mohs scale), Color: tan to grayish-brown, Luster: dull to vitreous, Crystal structure: Trigonal (granular), Cleavage: None, Specific gravity: 2.6-2.65

Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, typically during mountain-building events. This specimen shows signs of water-rounding from a river or beach environment.

Used as a decorative stone, in construction as crushed stone or railway ballast, and historically for stone tools due to its hardness and durability.

Quartzite is so hard that it will scratch glass and steel. It is more resistant to weathering than the sandstone it originated from, often forming the caps of ridges and mountains.

Identify by its extreme hardness and sugary, granular texture which distinguishes it from sandstone (it breaks through the grains rather than around them). Commonly found in ancient metamorphic belts and as river cobbles.