metamorphic

Tumbled quartzite (probable)

Quartzite, predominantly crystalline SiO₂

AI-generated identification · may be incorrect

Hardness about 7 Mohs; pinkish-purple and cream coloration, caused by iron oxides or minor impurities; granular, crystalline texture and vitreous-to-dull luster. Quartzite has no cleavage, uneven fracture, and typically high durability.

Identified September 1, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when quartz-rich sandstone was recrystallized under heat and pressure during metamorphism; individual specimens may be hundreds of millions to billions of years old. The rounded shape and smooth surface indicate human tumbling or natural abrasion.

Uses & applications

Used as aggregate, building and paving stone, architectural slabs, and decorative landscaping material; attractive pieces are sold as inexpensive lapidary or educational specimens.

Geological facts

Quartzite can resemble marble but is much harder and generally does not fizz with dilute hydrochloric acid. Purple tones may indicate iron staining or trace manganese rather than true amethyst.

Field identification & locations

Identify by testing for hardness against glass, observing abundant interlocking quartz grains, and checking for absence of carbonate fizz; common sources include metamorphic belts worldwide, especially Brazil, India, and the United States. Exact identification is uncertain from the photograph alone.