mineral

Banded agate (likely Montana/Columbia River-style agate)

Microcrystalline quartz, SiO₂ (chalcedony with mogánite; iron-oxide staining)

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; white, cream, tan, and brown concentric banding; waxy to dull luster; cryptocrystalline, with no visible cleavage and conchoidal fracture. The specimen appears naturally fractured or roughly cut, not glass or ceramic.

Identified August 29, 2026More mineral →

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At a glance

Common name: Banded agate (likely Montana/Columbia River-style agate)
Scientific name: Microcrystalline quartz, SiO₂ (chalcedony with mogánite; iron-oxide staining)
Category: mineral
Identified: August 29, 2026
Method: Standard

AI Estimated Value

About $5–$30 as a rough common specimen; $30–$150 if the banding polishes attractively or it is a substantial lapidary piece.

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 in volcanic rock, depositing successive layers of chalcedony and quartz. Individual bands may form over thousands to millions of years, commonly in Cenozoic basalt provinces; the regional occurrence near northeastern Washington is geologically plausible.

Uses & applications

Used for cabochons, slabs, carvings, ornaments, and lapidary collecting; less commonly as aggregate or decorative stone.

Geological facts

The curved “fortification” bands record changing chemistry and flow conditions during cavity filling. Dark lines are likely manganese or iron-bearing inclusions and fractures rather than true black minerals.

Field identification & locations

Identify by translucent edges, waxy feel, very hard silica, curved rhythmic bands, and inability to scratch it with a steel knife (though quartz can scratch glass). Common in Washington and neighboring Columbia Plateau volcanic terrains, often as agate nodules or seams.