metamorphic

Quartz-rich rock, likely milky quartz or quartzite

Quartz (SiO₂); probable quartzite if the specimen is a coherent rock

AI-generated identification · may be incorrect

White to translucent, vitreous to slightly sugary luster, with interlocking quartz grains and brown iron-oxide staining. Quartz hardness is Mohs 7, lacks cleavage, has uneven fracture, and specific gravity near 2.65.

Identified August 31, 2026More metamorphic →

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Physical properties

Formation & geological history

Quartzite forms when quartz-rich sandstone is recrystallized during metamorphism; milky quartz may instead crystallize from hydrothermal fluids in fractures. Exact age cannot be determined from the image.

Uses & applications

Used as crushed stone, aggregate, silica feedstock, and decorative stone; attractive pieces may be used in carvings or collections.

Geological facts

The sparkle comes from reflective quartz grain surfaces or fracture planes, while brown areas are likely limonite or hematite staining.

Field identification & locations

Common in metamorphic belts and hydrothermal veins worldwide, including the Appalachians, Alps, Brazil, Madagascar, and western United States. A glassy scratch on ordinary glass, absence of cleavage, and resistance to a steel knife support quartz; acid testing is generally uninformative.