metamorphic

Quartzite

Recrystallized Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Mohs hardness of 7, color ranging from orange-tan to rusty brown due to iron oxides, vitreous to dull luster, granoblastic texture with interlocking quartz grains.

Identified July 18, 2026More metamorphic →

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Physical properties

Mohs hardness of 7, color ranging from orange-tan to rusty brown due to iron oxides, vitreous to dull luster, granoblastic texture with interlocking quartz grains.

Formation & geological history

Formed when quartz-rich sandstone is subjected to intense heat and pressure during regional metamorphism, causing quartz grains to fuse together.

Uses & applications

Used in construction as road ballast, decorative stone for landscaping, and occasionally in glassmaking if high in purity.

Geological facts

Quartzite is so hard and durable that it often forms the resistant ridges and hilltops of old mountain ranges. It is harder than steel and can scratch glass easily.

Field identification & locations

Identify in the field by its sugary texture and extreme hardness. Unlike many sedimentary rocks, it will break through the grains rather than around them. Found globally in ancient mountain belts.