metamorphic

Quartz-rich sandstone or quartzite

Quartzite (mostly microcrystalline SiO₂), possibly silicified sandstone

AI-generated identification · may be incorrect

Hardness about 7 Mohs; pale tan to gray, vitreous to dull luster, granular crystalline texture, and no obvious cleavage. The weathered, iron-stained surface and sugary quartz appearance are consistent with quartz-rich rock, though the image cannot confirm whether it is sandstone or quartzite.

Identified September 7, 2026More metamorphic →

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Physical properties

Formation & geological history

Quartzite forms when quartz sandstone is recrystallized under metamorphic heat and pressure, commonly during mountain building; its exact geological age is indeterminate from the image. If weakly cemented rather than recrystallized, it may instead be sandstone.

Uses & applications

Used as crushed aggregate, road stone, riprap, building stone, and occasionally decorative or landscaping material; attractive pieces may be polished, but this specimen is not gem quality.

Geological facts

Quartzite is highly resistant to weathering and commonly forms ridges or durable boulders. Iron oxides can produce the tan, orange, and brown staining visible here.

Field identification & locations

Look for quartz grains fused into a hard, coherent mass; quartzite scratches glass and generally does not crumble along bedding, unlike sandstone. Common worldwide, especially in metamorphic mountain belts.