gemstone

Tumbled blue-green chalcedony (likely dyed)

Chalcedony, microcrystalline quartz (SiO₂)

AI-generated identification · may be incorrect

Smooth, rounded, polished pebble with blue-green color and waxy-to-glassy luster. Quartz hardness is about 6.5–7 Mohs; no visible cleavage, cryptocrystalline structure, and specific gravity near 2.6. The unusually vivid, even color suggests dyeing or surface treatment; turquoise or dyed agate are alternatives.

Identified August 25, 2026More gemstone →

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Physical properties

Formation & geological history

Chalcedony forms when silica-rich groundwater fills cavities and fractures, commonly in volcanic rocks, then is later tumbled and polished. Natural material may be Paleozoic to Cenozoic depending on its host deposit; treatment age cannot be determined visually.

Uses & applications

Used for inexpensive cabochons, beads, carvings, ornaments, and lapidary practice. Treated tumbled stones generally have modest commercial value.

Geological facts

Color alone is not diagnostic: blue-green chalcedony can resemble turquoise, chrysocolla, dyed quartz, or glass. A dye concentration in pits or cracks and color rubbing onto acetone-damp cotton would support treatment, though testing can damage the specimen.

Field identification & locations

The nearby Sabah/Borneo region commonly yields quartz- and silica-rich rocks, but this polished specimen cannot be localized confidently. Check translucency at the edges, hardness against glass, and dye pooling; avoid destructive tests if valuable.