mineral

Yellow chalcedony (likely lemon/citrine-colored agate)

Microcrystalline quartz, SiO₂ (chalcedony)

AI-generated identification · may be incorrect

Translucent pale yellow, waxy-to-vitreous luster, and cryptocrystalline quartz structure; no visible cleavage. Hardness is about 6.5–7 Mohs, with specific gravity near 2.60; the smoothly rounded surface indicates polishing or tumbling.

Identified September 18, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, precipitating microscopic quartz fibers, commonly in volcanic rocks. Its exact age depends on the host deposit; yellow color may result from iron staining or heat treatment.

Uses & applications

Used for cabochons, beads, carvings, ornamental objects, and polished specimens; durable but generally modestly priced unless color and translucency are exceptional.

Geological facts

Chalcedony is quartz too fine-grained to show ordinary crystal faces. Strong banding would support an agate identification, while uniform color favors chalcedony or treated material.

Field identification & locations

Common in volcanic terrains and found worldwide, notably Brazil, Uruguay, India, Madagascar, and the western United States. Confirm with hardness testing, a refractive-index test, and inspection for banding or dye concentration; avoid scratching the specimen if valuable.