metamorphic
Tumbled green-gray stone, likely aventurine quartzite
Quartz-rich quartzite, possibly fuchsite-bearing aventurine quartz (SiO₂)
AI-generated identification · may be incorrectHardness about 7 Mohs; blue-green/gray color, fine granular texture, and vitreous to dull luster. The rounded surface is tumbled and obscures crystal boundaries; faint sparkles may indicate mica inclusions.
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Physical properties
Hardness about 7 Mohs; blue-green/gray color, fine granular texture, and vitreous to dull luster. The rounded surface is tumbled and obscures crystal boundaries; faint sparkles may indicate mica inclusions.
Formation & geological history
Quartzite forms when quartz-rich sandstone is recrystallized under metamorphic heat and pressure, commonly during mountain-building. Its precise geological age and identity cannot be determined reliably from this photograph.
Uses & applications
Used as a tumbled decorative stone, lapidary material, and occasionally in beads, cabochons, and ornamental objects; quartzite also has construction uses when quarried as slab or aggregate.
Geological facts
Aventurine’s characteristic glitter, called aventurescence, comes from reflective mica or hematite inclusions. Similar-looking stones include serpentine, nephrite, gray quartzite, and dyed material.
Field identification & locations
Check for hardness: quartz-rich material should scratch ordinary glass, while a steel blade generally will not scratch it; inspect for mica glitter and a granular texture. Common quartzites occur worldwide, including India, Brazil, and the United States.
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