gemstone

Yellow agate/chalcedony cabochon

Microcrystalline quartz (SiO₂), likely yellow chalcedony or iron-stained agate

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; translucent honey-yellow color, waxy to vitreous luster, cryptocrystalline quartz structure, no visible cleavage, and typical specific gravity near 2.6. The polished oval surface and internal cloudy texture are consistent with chalcedony, though the image cannot confirm banding or treatments.

Identified September 15, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures in volcanic rock, with iron oxides producing yellow coloration; deposits range from Paleozoic to recent depending on locality. Common sources include Brazil, Uruguay, Madagascar, India, and Indonesia.

Uses & applications

Used for cabochons, beads, carvings, and ornamental objects; durable enough for jewelry but generally less valuable than fine transparent citrine or intensely colored agate.

Geological facts

Yellow color commonly results from hydrated iron oxides or heat treatment. Chalcedony is quartz composed of extremely small interlocking crystals rather than large visible crystals.

Field identification & locations

Identify by its glass-scratching hardness, waxy translucence, absence of cleavage, and possible conchoidal fracture; it should not fizz in dilute acid. Natural banding, dye concentration, and heat-treatment evidence require close inspection or testing.