mineral

Chalcedony (likely blue agate) knapped into an arrowhead

Microcrystalline quartz, SiO₂ (chalcedony)

AI-generated identification · may be incorrect

Translucent pale-blue material with darker inclusions and a waxy luster; quartz hardness about 6.5–7 Mohs, trigonal crystal structure at the microscopic level, and no cleavage. The flaked, pointed shape is human-made.

Identified October 1, 2026More mineral →

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Physical properties

Formation & geological history

Chalcedony forms when silica-rich fluids fill cavities or fractures, commonly in volcanic rocks; deposits range from ancient to geologically recent. The arrowhead was shaped by knapping, but its age and authenticity cannot be determined from the photo.

Uses & applications

Chalcedony is used for beads, carvings, and ornamental objects; the shaped piece may be a replica, artifact, or collectible.

Geological facts

Blue color can result from fine mineral inclusions or structural scattering; appearance alone does not establish the stone variety or archaeological age.

Field identification & locations

Look for waxy translucence and conchoidal fracture; a genuine knapped point typically shows deliberate flake scars and edge shaping. Chalcedony occurs worldwide, including Brazil, India, and the western United States.