Quartzite

Hardness 7 on Mohs scale; color is generally white, gray, or tan, but iron oxides can produce yellowish, orange, or reddish hues as seen here; waxy to vitreous luster; granular texture; very high resistance to weathering.

Formed through the metamorphism of quartz-rich sandstone. Under intense heat and pressure, quartz grains recrystallize and fuse together, eliminating most of the original sedimentary pore space. This specimen appears water-worn, suggesting a fluvial (river) environment.

Used widely in construction as crushed stone for road ballast, roofing granules, and as a decorative stone. High-purity quartzite is used to produce silica sand for glassmaking and silicon for electronics.

Quartzite is so tough that it often outlasts the surrounding rocks, forming prominent ridges and peaks in mountain ranges. It is harder than steel and will easily scratch a glass plate.

Look for a sugary, granular appearance that sparkles under light. Unlike sandstone, quartzite breaks across the quartz grains rather than around them. It is commonly found in riverbeds and mountainous terrain containing ancient metamorphic belts.