Rock Identifier
Pink chalcedony (pink agate-like quartz) (Microcrystalline quartz, SiO₂ (chalcedony; likely iron-bearing)) — mineral
mineral

Pink chalcedony (pink agate-like quartz)

Microcrystalline quartz, SiO₂ (chalcedony; likely iron-bearing)

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent pink, cream, and gray-brown zones with a waxy to vitreous luster. It has cryptocrystalline quartz structure, no obvious cleavage, conchoidal fracture, and typical specific gravity near 2.60.

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Physical properties

Hardness 6.5–7 Mohs; translucent pink, cream, and gray-brown zones with a waxy to vitreous luster. It has cryptocrystalline quartz structure, no obvious cleavage, conchoidal fracture, and typical specific gravity near 2.60.

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures in volcanic rocks, depositing microcrystalline quartz; coloration commonly comes from iron or other trace impurities. The specimen’s exact geological age and locality cannot be determined from the image.

Uses & applications

Used as an ornamental stone, beads, cabochons, carvings, and small polished specimens; occasionally sold as pink agate or rose chalcedony.

Geological facts

Chalcedony is quartz composed of extremely small interlocking crystals, so individual crystal faces are usually absent. Its color and banding can overlap with jasper, agate, and common quartz varieties.

Field identification & locations

Identify it by its smooth waxy appearance, conchoidal fracture, lack of cleavage, and ability to scratch ordinary glass; a streak test is white. Common sources include volcanic regions of Brazil, Uruguay, India, Madagascar, and the western United States.