mineral

Tumbled blue chalcedony (likely common blue quartz)

Microcrystalline quartz, SiO₂; chalcedony variety

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; pale blue-gray with cream/brown iron-stained areas, waxy to vitreous luster, and no visible cleavage. The rounded shape indicates tumbling; specific gravity is about 2.6.

Identified August 11, 2026More mineral →

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Physical properties

Hardness 6.5–7 Mohs; pale blue-gray with cream/brown iron-stained areas, waxy to vitreous luster, and no visible cleavage. The rounded shape indicates tumbling; specific gravity is about 2.6.

Formation & geological history

Forms when silica-rich groundwater deposits microscopic quartz fibers in cavities and fractures, commonly in volcanic rocks. Deposits range from ancient to modern and are widespread worldwide.

Uses & applications

Used as an ornamental and lapidary stone, for cabochons, carvings, beads, and inexpensive jewelry. Small tumbled pieces typically have modest collector value.

Geological facts

Blue chalcedony’s color can result from finely dispersed minerals, microscopic inclusions, or slight iron staining. It may resemble dyed agate or common quartz.

Field identification & locations

Identify it by its waxy appearance, conchoidal fracture, translucency at thin edges, and resistance to scratching by a steel knife; glass should not scratch it. Common sources include Brazil, Namibia, Turkey, and the western United States.