gemstone

Tumbled blue chalcedony (likely blue lace agate)

Microcrystalline quartz, SiO₂; chalcedony variety, possibly banded blue lace agate

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; translucent pale blue to lavender with whitish curved banding, waxy-to-vitreous luster, and no visible cleavage. Specific gravity is approximately 2.58–2.64; the rounded shape indicates tumbling and polishing.

Identified August 18, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures in volcanic rocks, depositing microcrystalline quartz in layers. Blue lace agate is especially associated with Precambrian volcanic terrains of Namibia and southern Africa.

Uses & applications

Used for cabochons, beads, carvings, ornamental objects, and inexpensive jewelry; polished pieces are popular among mineral collectors.

Geological facts

Blue coloration may result from trace minerals or microscopic inclusions, and some commercial material may be dyed. Chalcedony commonly produces a smooth, glassy-to-waxy polish.

Field identification & locations

Identify by its waxy translucency, curved internal bands, quartz-like hardness, and inability to scratch with a fingernail or copper coin; a steel file generally will not scratch it easily. Common sources include Namibia, Brazil, Madagascar, and Uruguay.