mineral

Tumbled chalcedony (likely moss or plume agate)

Microcrystalline quartz, SiO₂; chalcedony with possible iron/manganese inclusions

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; translucent gray-beige with rusty brown internal clouding, waxy to dull luster, no visible cleavage, cryptocrystalline structure, and specific gravity about 2.60–2.65.

Identified September 13, 2026More mineral →

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Physical properties

Mohs hardness 6.5–7; translucent gray-beige with rusty brown internal clouding, waxy to dull luster, no visible cleavage, cryptocrystalline structure, and specific gravity about 2.60–2.65.

Formation & geological history

Silica-rich groundwater filled cavities or fractures in volcanic rock, later depositing chalcedony and iron-oxide inclusions; such material commonly formed during Cenozoic volcanic activity, though age depends on locality.

Uses & applications

Used for beads, cabochons, carvings, decorative stone, and inexpensive polished specimens; generally more ornamental than industrial.

Geological facts

The rounded shape and glossy surface indicate human tumbling and polishing. Brown or green patterns in chalcedony are often called moss, plume, sagenite, or scenic agate depending on inclusion form.

Field identification & locations

Identify by its glassy-to-waxy appearance, translucency, hardness, and lack of cleavage; it should scratch glass but not be scratched by a steel knife. Common sources include Oregon, Washington, Brazil, Uruguay, India, and Madagascar.