mineral

Polished jasper and banded agate specimens

Microcrystalline quartz (chalcedony), SiO₂, with iron-oxide and other inclusions

AI-generated identification · may be incorrect

The larger piece appears to be brecciated/polychrome jasper with a gray chalcedony or agate zone; the smaller is dark polished jasper or agate. Hardness is about 6.5–7 Mohs, with waxy to vitreous luster, opaque-to-translucent areas, and no obvious cleavage.

Identified August 16, 2026More mineral →

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Physical properties

Formation & geological history

These silica-rich materials formed when groundwater deposited chalcedony in cavities or fractures, with iron oxides producing red, brown, and yellow colors; brecciation and later cementation created the mottled pattern. Ages vary widely by deposit, commonly Paleozoic to Cenozoic.

Uses & applications

Used for cabochons, beads, carvings, tumbled stones, ornamental objects, and lapidary collections; attractive patterns command higher prices.

Geological facts

Jasper is opaque chalcedony, whereas agate is generally translucent and banded; both are varieties of quartz rather than separate mineral species.

Field identification & locations

Identify by testing hardness against glass, observing waxy luster and conchoidal fracture, and checking that colors are natural rather than dye concentrated in cracks. Common sources include Madagascar, Brazil, India, Mexico, and the western United States.