mineral

Chalcedony (possibly lavender or gray agate)

Microcrystalline quartz, SiO₂; fibrous quartz aggregate

AI-generated identification · may be incorrect

Typically Mohs hardness 6.5–7, waxy to vitreous luster, translucent gray-lavender color, and conchoidal fracture with no cleavage. The cloudy, botryoidal texture and subtle concentric zoning are consistent with chalcedony, though the photograph cannot confirm the identification.

Identified August 23, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater precipitates in cavities, fractures, or volcanic vesicles, commonly replacing or lining host rock. It can form from Paleogene to Recent deposits, depending on locality.

Uses & applications

Used as ornamental stone, cabochons, carvings, beads, and lapidary material; durable varieties are also used for small tools and decorative objects.

Geological facts

Chalcedony is a cryptocrystalline quartz variety composed of microscopic quartz fibers. Lavender coloration may result from trace iron, manganese, or inclusions, while brown areas may be iron oxides or host-rock material.

Field identification & locations

Identify it by its waxy surface, hardness, translucency, and conchoidal fracture; it should scratch glass but not be scratched by a steel knife. Common sources include Brazil, Uruguay, India, Madagascar, Turkey, and the western United States.