mineral
Dyed and polished agate pebble
Microcrystalline quartz (SiO₂), likely chalcedony/agate with blue dye
AI-generated identification · may be incorrectTumbled, smooth, opaque cream-brown chalcedony containing dark blue dyed bands or surface-filled areas. Quartz hardness is about 6.5–7 Mohs, vitreous to waxy luster, cryptocrystalline structure, and no visible cleavage; the blue color appears artificial.
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Physical properties
Tumbled, smooth, opaque cream-brown chalcedony containing dark blue dyed bands or surface-filled areas. Quartz hardness is about 6.5–7 Mohs, vitreous to waxy luster, cryptocrystalline structure, and no visible cleavage; the blue color appears artificial.
Formation & geological history
Agate forms when silica-rich groundwater fills cavities in volcanic rock, commonly during the Paleogene to recent geologic eras. This specimen has been cut or shaped, polished, and likely artificially dyed after formation.
Uses & applications
Used as a decorative stone, lapidary material, paperweight, or low-cost jewelry component; it has little industrial significance in this form.
Geological facts
Agate commonly shows concentric banding, but vivid uniform blue is a strong indicator of dye treatment. Dye may concentrate along pores, fractures, or natural band boundaries.
Field identification & locations
Look for waxy luster, very fine texture, conchoidal fracture, and hardness sufficient to scratch glass; natural blue agate is uncommon. Common sources include Brazil, Uruguay, India, Madagascar, and Mexico.
