mineral

Polished carnelian/chalcedony agate

Microcrystalline quartz (SiO₂), chiefly chalcedony with iron-oxide coloring

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent orange, peach, cream, and brown zones; waxy to vitreous luster; cryptocrystalline quartz with no cleavage and conchoidal fracture. The lower brown area may contain druzy quartz and iron-rich inclusions.

Identified August 10, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities in volcanic rock, depositing layered chalcedony and quartz; iron oxides create red-orange-brown colors. Such agates commonly formed in Cenozoic to older volcanic environments.

Uses & applications

Used for cabochons, beads, carvings, polished stones, and inexpensive ornamental objects; valued for attractive banding, translucency, and polish.

Geological facts

Carnelian is the orange-red variety of chalcedony, while agate is characterized by internal banding or contrasting zones; one specimen can reasonably be sold under both names.

Field identification & locations

Identify by testing its glassy/waxy surface, lack of cleavage, translucency, and hardness sufficient to scratch ordinary glass. Common sources include Brazil, Uruguay, India, Madagascar, and the western United States.