sedimentary

Weathered vuggy quartz-rich rock (probable silicified limestone or quartz breccia)

Microcrystalline quartz (SiO₂) with calcite (CaCO₃), iron oxides, and minor clay minerals

AI-generated identification · may be incorrect

Hardness is roughly 3–7 depending on the spot: quartz-rich areas scratch glass, while calcite-rich areas are softer and may fizz weakly with dilute acid. It is gray, cream, and rusty brown, with dull to glassy luster, irregular granular texture, and numerous cavities (vugs); no obvious cleavage is visible.

Identified August 10, 2026More sedimentary →

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At a glance

Common name: Weathered vuggy quartz-rich rock (probable silicified limestone or quartz breccia)
Scientific name: Microcrystalline quartz (SiO₂) with calcite (CaCO₃), iron oxides, and minor clay minerals
Category: sedimentary
Identified: August 10, 2026
Method: Standard

AI Estimated Value

Approximately $5–$25 for a common rough specimen; $30–$100+ if cavities contain attractive crystals or the piece polishes well.

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

Likely formed when silica-rich fluids replaced or cemented a carbonate-rich sedimentary rock, leaving cavities later lined or partly filled by quartz and iron oxides. The exact geological age cannot be determined from the image; such rocks occur in hydrothermal, karst, and weathered mineralized settings.

Uses & applications

Used mainly as a collector specimen, decorative stone, or source material for lapidary work if sound enough to polish; it has little industrial value in this rough form.

Geological facts

The cavities may be solution voids, gas-like vugs, or weathered-out mineral pockets rather than fossils. Rusty colors commonly reflect hematite or goethite staining.

Field identification & locations

Look for a glass-scratching quartz-rich matrix, possible acid reaction on pale carbonate patches, and iron staining around cavities. Commonly found in hydrothermal veins, silicified limestone zones, and exposed carbonate terrains.