metamorphic
Blue aventurine (likely dyed quartzite)
Quartz-rich quartzite, primarily silicon dioxide (SiO₂); identification is uncertain from the image
AI-generated identification · may be incorrectDeep cobalt-blue, opaque, smoothly polished cabochon with a fine-grained appearance and vitreous-to-waxy luster. Quartz has Mohs hardness 7 and a hexagonal crystal structure, but a compact quartzite shows no obvious cleavage.
Identified More metamorphic →
Explore Blue aventurine (likely dyed quartzite) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Deep cobalt-blue, opaque, smoothly polished cabochon with a fine-grained appearance and vitreous-to-waxy luster. Quartz has Mohs hardness 7 and a hexagonal crystal structure, but a compact quartzite shows no obvious cleavage.
Formation & geological history
Quartzite forms when quartz-rich sandstone is recrystallized under heat and pressure; its grains interlock. The vivid, uniform blue suggests the stone may have been artificially dyed; its geological age depends on its source.
Uses & applications
Polished cabochons are used in jewelry and as collectible decorative stones; quartzite is also used for building and landscaping.
Geological facts
Blue stones sold as aventurine may be dyed quartzite or other quartz-rich material; natural blue aventurine is uncommon.
Field identification & locations
Check for color concentrated in cracks or uneven patches, which can indicate dye; a hardness or streak test is more reliable but may damage the cabochon. Quartzite occurs worldwide, including Brazil, India, and the United States.
More like this
