mineral

Pink chalcedony (likely rough agate/chalcedony)

Microcrystalline quartz, SiO₂; chalcedony variety, possibly iron-bearing

AI-generated identification · may be incorrect

Typically Mohs hardness 6.5–7, vitreous to waxy luster, translucent to opaque, and pink to reddish-brown from iron impurities. It has cryptocrystalline quartz structure, no obvious cleavage, conchoidal fracture, and specific gravity about 2.6.

Identified August 11, 2026More mineral →

Explore Pink chalcedony (likely rough agate/chalcedony) in the encyclopedia →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures in volcanic rock, commonly by low-temperature precipitation; the specimen may be Cenozoic or older depending on its source. The image suggests a weathered, naturally rounded rough fragment.

Uses & applications

Used for carvings, cabochons, beads, ornamental stone, and lapidary work; massive low-grade pieces have modest decorative value.

Geological facts

Chalcedony can show subtle banding, botryoidal surfaces, or color zoning; iron oxides commonly produce pink, orange, and brown hues. Identification is more reliable with hardness and specific-gravity tests than by color alone.

Field identification & locations

Common in volcanic terrains and alluvial gravels worldwide, including Brazil, Uruguay, India, Madagascar, Mexico, and the western United States. A glass-scratching test and lack of cleavage support quartz, while acid produces no reaction.