gemstone

Yellow chalcedony cabochon

Chalcedony, microcrystalline quartz (SiO₂)

AI-generated identification · may be incorrect

Polished, translucent honey-yellow stone with a waxy-to-vitreous luster and no visible crystal faces. Quartz hardness is 7 Mohs; chalcedony has a trigonal crystal structure at the microscopic level and no distinct cleavage. The bright sheen may be a reflection rather than true chatoyancy.

Identified October 11, 2026More gemstone →

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Physical properties

Formation & geological history

Silica-rich fluids deposited microscopic quartz in rock cavities or fractures; chalcedony forms in many geological settings, from ancient volcanic rocks to sedimentary formations. The yellow color commonly comes from iron impurities or treatment; the image alone cannot establish age or natural versus treated color.

Uses & applications

Used for cabochons, beads, and ornamental objects; chalcedony is also used for carvings and historically for seals and tools.

Geological facts

Chalcedony is a compact, fibrous variety of quartz, and its broad color range includes yellow, blue, gray, and reddish forms.

Field identification & locations

Check for a smooth, glassy-to-waxy surface and hardness near 7; confirm identity and treatment with gemological testing, since similar-looking glass or dyed stones exist. Common sources include Brazil, India, Madagascar, and Uruguay.