mineral

Tumbled blue chalcedony/agate (likely glassy silica material)

Microcrystalline quartz, SiO₂; possibly blue chalcedony or dyed agate

AI-generated identification · may be incorrect

Translucent blue-gray pieces with waxy to vitreous luster and conchoidal fracture; quartz hardness is about 7 Mohs, no cleavage, and specific gravity about 2.6. The larger piece appears polished or naturally water-worn, with pale mottling and possible iron/mineral inclusions.

Identified August 15, 2026More mineral →

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Physical properties

Formation & geological history

Chalcedony forms when silica-rich groundwater fills cavities and fractures, commonly in volcanic rocks; agate is its banded variety. Formation ages vary widely, from relatively young volcanic settings to Paleozoic and older deposits.

Uses & applications

Used for cabochons, beads, carvings, tumbled stones, and lapidary decoration; attractive specimens generally have strong translucency, color, or banding.

Geological facts

Blue chalcedony may be naturally colored, heat-treated, or dyed; uniform vivid blue often indicates treatment. The photograph alone cannot distinguish chalcedony from blue slag glass or other treated silica.

Field identification & locations

Common sources include Turkey, Namibia, Brazil, Madagascar, and the United States. A steel file should not scratch quartz, while glass can; a 10× loupe may reveal natural microcrystalline texture rather than bubbles.