mineral

Blue chalcedony (probable)

Microcrystalline quartz, SiO₂

AI-generated identification · may be incorrect

A small rough, bluish-gray to brown translucent specimen with waxy luster and uneven fracture; quartz hardness is about 7 Mohs, with no cleavage and trigonal microcrystalline structure. The coloration may reflect inclusions or weathering.

Identified August 27, 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; individual deposits range from ancient to recent. The photograph alone cannot establish its exact geological age.

Uses & applications

Used for beads, carvings, cabochons, and ornamental stone; attractive blue material can have modest jewelry value. Lower-grade pieces are primarily collector specimens.

Geological facts

Chalcedony is a fibrous aggregate of quartz and commonly includes moganite. Its apparent blue color can overlap with blue quartz, chrysocolla-bearing chalcedony, or dyed material.

Field identification & locations

Common sources include Brazil, Uruguay, Namibia, Turkey, and the western United States. Test identification with a steel file or streak test only on an inconspicuous area; genuine quartz will not scratch easily and leaves a white streak.