igneous, sedimentary, metamorphic

Mixed collection of common river stones

Varied lithologies, visibly including quartz-rich rock, dark mafic rock, sandstone, and purple quartz-bearing material

AI-generated identification · may be incorrect

Mostly rounded, water-worn cobbles with dull to glassy luster; apparent hardness ranges about Mohs 3–7, depending on specimen. Colors include gray, brown, green, black, cream, and purple; individual crystal structures and cleavage vary.

Identified August 11, 2026More igneous, sedimentary, metamorphic →

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At a glance

Common name: Mixed collection of common river stones
Scientific name: Varied lithologies, visibly including quartz-rich rock, dark mafic rock, sandstone, and purple quartz-bearing material
Category: igneous, sedimentary, metamorphic
Identified: August 11, 2026
Method: Standard

AI Estimated Value

Typically $1–$10 per ordinary cobble; attractive lapidary pieces or confirmed minerals may range from $10–$50+, depending on identity, size, and finish.

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

These are likely glacial or stream-rounded fragments derived from multiple source rocks; their ages cannot be determined from the image and may range from ancient to relatively young geological formations.

Uses & applications

Commonly used for landscaping, decorative stone, craft projects, and educational collections; attractive purple or patterned pieces may be sold as lapidary rough.

Geological facts

The purple specimen may be quartz-rich jasper or rhyolite, but color alone cannot confirm amethyst. Several pieces appear sedimentary or metamorphic, while others may be volcanic.

Field identification & locations

Field identification requires inspecting grain size, layering, foliation, acid reaction, streak, and hardness; a close-up and locality are needed for reliable names. Rounded surfaces indicate transport by water or ice.

Other igneous, sedimentary, metamorphic specimens

See all

Quartz

Quartz (SiO₂)

Mineral

Quartz

SiO2 (Silicon dioxide)

mineral

Quartz

Silicon Dioxide (SiO2)

mineral

Unidentifiable Specimen

Undetermined

Unknown

Mixed river stones and gravel

Polymictic alluvial clasts; individual pieces may include quartzite, granite, basalt, sandstone, limestone, and slate

igneous, sedimentary, metamorphic

Mixed stream gravel and common rock specimens

Predominantly quartz-rich granitoid, quartzite, sandstone, shale/slate, and mafic volcanic fragments; exact species cannot be determined confidently from the image

igneous, sedimentary, metamorphic