mineral
Tumbled blue chalcedony (possibly blue agate)
Microcrystalline quartz, SiO₂; chalcedony variety
AI-generated identification · may be incorrectPale blue-white, translucent to opaque, with a waxy-to-vitreous luster and no visible cleavage; Mohs hardness 6.5–7. The image appears to show a polished, rounded specimen, but fine details are unclear.
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Physical properties
Pale blue-white, translucent to opaque, with a waxy-to-vitreous luster and no visible cleavage; Mohs hardness 6.5–7. The image appears to show a polished, rounded specimen, but fine details are unclear.
Formation & geological history
Chalcedony forms when silica-rich fluids deposit microscopic quartz in cavities and fractures, commonly in volcanic rocks. The specimen’s geological age and source cannot be determined from the image.
Uses & applications
Used for beads, cabochons, carvings, and ornamental objects; also collected as a polished stone.
Geological facts
Chalcedony is made of extremely fine quartz crystals, so individual crystals generally are not visible without magnification.
Field identification & locations
Look for a smooth, compact surface, waxy luster, and hardness sufficient to scratch glass; blue coloration alone does not confirm agate banding. Common sources include Brazil, Uruguay, India, and Madagascar.
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