gemstone

Polished moss agate (likely dendritic/chalcedony agate)

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

AI-generated identification · may be incorrect

Typically Mohs 6.5–7, translucent gray-white to cream, with a waxy to vitreous luster and no visible cleavage; inclusions create rusty brown and dark dendritic markings. Specific gravity is about 2.60–2.65.

Identified August 26, 2026More gemstone →

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At a glance

Common name: Polished moss agate (likely dendritic/chalcedony agate)
Scientific name: Microcrystalline quartz, SiO₂ (chalcedony with iron-oxide and possible manganese inclusions)
Category: gemstone
Identified: August 26, 2026
Method: Standard

AI Estimated Value

About $5–$25 for a common polished piece; $30–$100+ if unusually translucent, well-patterned, or finely finished.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures in volcanic rocks, depositing layered chalcedony and later iron/manganese oxides. Individual agate growth may span millions of years, commonly in Cenozoic or older volcanic terrains.

Uses & applications

Used for cabochons, carvings, beads, tumbled stones, and ornamental objects; attractive patterned pieces have modest collector value.

Geological facts

“Moss agate” is a trade name rather than a separate mineral species; its moss-like patterns are inclusions, not crystal growth. The specimen appears polished and may have surface iron staining.

Field identification & locations

Identify by its fine-grained, glassy-to-waxy silica body, translucency, conchoidal fracture, and non-geometric inclusions; common sources include India, Brazil, Uruguay, Mexico, and the United States. A steel file should not readily scratch it, though testing may damage the polish.