mineral

Polished blue lace agate slice

Chalcedony (microcrystalline quartz), SiO₂, commonly with blue-gray banding and a druzy quartz center

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; blue-gray to white concentric bands, waxy to vitreous luster, cryptocrystalline quartz, and no visible cleavage. The cavity contains sparkling drusy quartz crystals; the specimen is cut and polished.

Identified August 15, 2026More mineral →

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Physical properties

Formation & geological history

Agate forms when silica-rich groundwater fills vesicles in volcanic lava, depositing chalcedony in successive bands; later quartz crystals may line cavities. Formation is generally Cenozoic to older, depending on the host volcanic rock.

Uses & applications

Used for ornamental slabs, cabochons, carvings, jewelry, bookends, and decorative objects. Collectors value strong banding, saturated color, attractive polish, and intact druzy centers.

Geological facts

Blue lace agate is associated especially with Namibia and South Africa, while agates broadly occur worldwide. Natural blue lace agate is typically pale blue; intensely bright blue pieces may be dyed.

Field identification & locations

Identify it by translucent edges, curved banding, waxy chalcedony texture, and absence of cleavage; glass-like bubbles or uniform artificial color suggest imitation or dyeing. Common sources include Brazil, Uruguay, Mexico, Namibia, and the United States.