mineral

Polished banded agate (likely Botswana agate)

Banded chalcedony, microcrystalline quartz (SiO₂)

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; brown, cream, and gray curved bands with a waxy-to-vitreous polish. Trigonal quartz; no visible cleavage, uneven to conchoidal fracture; specific gravity about 2.6.

Identified October 4, 2026More mineral →

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Physical properties

Mohs hardness 6.5–7; brown, cream, and gray curved bands with a waxy-to-vitreous polish. Trigonal quartz; no visible cleavage, uneven to conchoidal fracture; specific gravity about 2.6.

Formation & geological history

Silica-rich groundwater deposited successive chalcedony layers in rock cavities, later polished into a heart. Agates form across a wide range of geological ages, commonly in volcanic rocks.

Uses & applications

Used for jewelry, ornaments, and lapidary collecting; agate is also used in small decorative objects.

Geological facts

The specimen’s regular brown-and-cream bands are characteristic of banded chalcedony; exact locality cannot be determined from appearance alone.

Field identification & locations

Identify by its fine, curved color bands, translucency at thin edges, and hard, glassy polish. Agates occur worldwide, including Brazil, Uruguay, India, and Botswana.