Quartzite Cobble

Hardness: 7 (Mohs), Color: Pinkish-grey to lavender-tan, Luster: Dull to vitreous when wet, Structure: Granular/Granoblastic, SG: 2.6-2.7

Formed through the regional metamorphism of quartz-rich sandstone. High heat and pressure cause the quartz grains to recrystallize and interlock. This specific specimen has been rounded by fluvial (river) or glacial transport.

Commonly used in construction as crushed stone for road ballast, as decorative landscaping stones, and historically as a material for stone tools due to its durability.

Quartzite is so hard that it will scratch glass and steel. Unlike sandstone, which breaks around the grains, quartzite breaks through the grains due to its dense, interlocking structure.

Identify in the field by its hardness and granular texture that sparkles slightly in light. Look for it along riverbeds and glacial moraines. Collectors value unique colors or perfectly rounded shapes.