mineral

Tumbled blue chalcedony or blue agate

Microcrystalline quartz (SiO₂), likely chalcedony with possible agate banding

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; pale blue-gray with translucent white areas, vitreous to waxy luster, and no visible cleavage. The rounded, polished shape indicates tumbling; exact identification is limited by the image.

Identified September 4, 2026More mineral →

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Physical properties

Formation & geological history

Silica-rich groundwater deposited microscopic quartz fibers in cavities or fractures, commonly in volcanic rocks; formation ages vary widely, from relatively young deposits to Paleozoic and older host rocks.

Uses & applications

Used for inexpensive cabochons, beads, carvings, ornaments, and lapidary collections; polished pieces have modest jewelry value.

Geological facts

Blue chalcedony is typically colored by trace minerals or microscopic inclusions, while agate is distinguished by recognizable internal banding. The specimen appears polished rather than naturally weathered.

Field identification & locations

Common sources include Brazil, Uruguay, India, Madagascar, Namibia, and the United States. Field clues are waxy luster, translucency, conchoidal fracture, and inability to scratch it with a steel knife; quartz should scratch glass.