metamorphic

Quartzite

Quartz-rich quartzite, composed predominantly of recrystallized quartz (SiO₂)

AI-generated identification · may be incorrect

Pale gray to tan, granular and sparkly with a massive texture; quartz hardness is 7 Mohs, vitreous to slightly sugary luster, and no distinct cleavage. The photo suggests quartzite, though composition cannot be confirmed visually.

Identified October 14, 2026More metamorphic →

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Physical properties

Formation & geological history

Forms when quartz-rich sandstone is recrystallized by heat and pressure, commonly during regional metamorphism; its age depends on the original sandstone and metamorphic event.

Uses & applications

Used as crushed stone, construction aggregate, paving and decorative stone; attractive pieces may be collected.

Geological facts

Interlocking quartz grains make sound quartzite very hard and resistant to weathering; it can resemble marble but does not fizz with dilute acid.

Field identification & locations

Look for a hard, silica-rich rock with a fused, sugary grain texture; it commonly occurs in metamorphic mountain belts. Estimated value: about $0–$10 for an ordinary loose specimen; more if polished or unusually attractive.