gemstone

Polished agate or jasper slice

Microcrystalline quartz (chalcedony), SiO₂, possibly iron-oxide-bearing jasper

AI-generated identification · may be incorrect

Visible specimen is a polished, curved slab with a gray-white translucent to opaque interior and a salmon-orange rim. Quartz hardness is about 6.5–7 Mohs, with vitreous to waxy luster; the apparent banding likely reflects chalcedony and iron-oxide inclusions.

Identified September 1, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, depositing chalcedony in layers; orange coloration commonly comes from hematite or limonite. Such material is generally Cenozoic to older, depending on its host volcanic rock and locality.

Uses & applications

Used for cabochons, beads, carvings, polished slabs, countertops, and decorative objects; quality is primarily determined by pattern, translucency, polish, and size.

Geological facts

Agate is the banded variety of chalcedony, while jasper is typically more opaque and impurity-rich; many commercial pieces combine both textures.

Field identification & locations

Identify it by its very fine texture, strong polish, conchoidal fracture, and lack of visible coarse grains or cleavage. Common sources include Brazil, Uruguay, Mexico, India, Madagascar, and the western United States.