mineral

Blue glassy tumbled stone, likely blue chalcedony or slag glass

Chalcedony (microcrystalline SiO₂), possibly man-made blue glass

AI-generated identification · may be incorrect

Smooth, rounded, translucent blue body with a waxy-to-glassy luster; chalcedony hardness is about 6.5–7 Mohs, with no visible cleavage and cryptocrystalline structure. The image alone cannot reliably distinguish natural chalcedony from dyed quartz or glass.

Identified September 12, 2026More mineral →

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Physical properties

Formation & geological history

Natural blue chalcedony forms when silica-rich fluids deposit microcrystalline quartz in volcanic cavities, commonly during the Cenozoic and older volcanic episodes. Artificial blue glass is melted silica with colorants and may show bubbles or flow lines.

Uses & applications

Blue chalcedony is used for cabochons, beads, carvings, and polished specimens; glass is mainly decorative. Common-quality pieces have modest market value.

Geological facts

Natural blue chalcedony is typically evenly translucent and waxy, while glass often has spherical bubbles, conchoidal fractures, and a distinctly vitreous surface.

Field identification & locations

Common sources include Namibia, Turkey, Indonesia, Brazil, and the United States. Check hardness, magnification, bubbles, and refractive behavior; definitive identification may require gemological testing.