metamorphic
Tumbled quartzite or quartz-rich stone
Quartzite; predominantly microcrystalline quartz (SiO₂)
AI-generated identification · may be incorrectHardness about 7 Mohs; cream-white with brown/gray iron-oxide staining, dull to slightly waxy luster, massive granular texture, and no obvious cleavage. The rounded shape indicates tumbling or natural abrasion.
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Physical properties
Hardness about 7 Mohs; cream-white with brown/gray iron-oxide staining, dull to slightly waxy luster, massive granular texture, and no obvious cleavage. The rounded shape indicates tumbling or natural abrasion.
Formation & geological history
Quartzite forms when quartz-rich sandstone is recrystallized under heat and pressure during metamorphism, commonly from Precambrian to younger mountain-building events. Exact origin and age cannot be determined from the image alone.
Uses & applications
Used as durable aggregate, road stone, building material, and decorative stone; small polished pieces are inexpensive craft or lapidary specimens.
Geological facts
Quartzite commonly resembles marble but is much harder and typically resists scratching by a steel knife. A glass-scratch test or hardness comparison can help confirm quartz-rich composition.
Field identification & locations
Common in metamorphic mountain belts worldwide, including Brazil, India, the United States, and Scandinavia. Identify it by its hardness, sugary quartz texture, lack of strong cleavage, and resistance to dilute acid.
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