mineral

Tumbled agate (likely carnelian/botryoidal chalcedony)

Microcrystalline quartz, SiO₂; chalcedony with iron-oxide coloration

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent brown, honey, cream, and orange bands with a waxy to vitreous luster. Massive cryptocrystalline quartz, with no visible cleavage and conchoidal fracture.

Identified September 16, 2026More mineral →

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Physical properties

Hardness 6.5–7 Mohs; translucent brown, honey, cream, and orange bands with a waxy to vitreous luster. Massive cryptocrystalline quartz, with no visible cleavage and conchoidal fracture.

Formation & geological history

Forms when silica-rich groundwater fills cavities in volcanic rocks, depositing chalcedony and later quartz; iron oxides create orange-brown colors. The specimen is naturally ancient but has been polished into a modern tumble.

Uses & applications

Used as an ornamental stone, bead, cabochon, carving material, and inexpensive jewelry or craft stone.

Geological facts

Agate’s fine banding reflects repeated changes in fluid chemistry during cavity filling; “carnelian” refers to orange-red chalcedony, while “moss” or “plume” varieties contain mineral inclusions.

Field identification & locations

Identify by translucent waxy appearance, curved/concentric color zoning, hardness sufficient to scratch glass, and lack of glittery crystal faces; common sources include Brazil, Uruguay, India, Madagascar, and the western United States.