metamorphic

Quartz-bearing metamorphic rock, possibly quartzite or hornfels

Mostly quartz (SiO₂), with probable iron-oxide and dark silicate minerals

AI-generated identification · may be incorrect

Gray-white, translucent-to-opaque granular material with vitreous to dull luster and irregular fracture; likely hardness about 6–7 Mohs. The dark brown weathered rind suggests iron oxidation or a fine-grained host rock; exact identification is limited by the photo.

Identified September 4, 2026More metamorphic →

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Physical properties

Formation & geological history

Likely formed by metamorphism that recrystallized silica-rich sediment or altered an adjacent rock, followed by surface weathering; age cannot be determined visually. Common in contact-metamorphic zones and metamorphosed sedimentary terrains.

Uses & applications

Quartzite is used as crushed stone, aggregate, building stone, and occasionally decorative material; attractive pieces may be collected but are usually low-value.

Geological facts

Quartz-rich zones commonly form resistant knobs and boulders because quartz withstands weathering. A white streak and lack of reaction to dilute acid would support quartzite over carbonate rock.

Field identification & locations

Look for interlocking quartz grains, very high scratch resistance, and no cleavage; a steel nail should not scratch fresh quartz-rich surfaces. Common worldwide, especially near metamorphic belts and intrusive contacts.