sedimentary

Mixed river gravel, prominently iron-stained chert/jasper

Microcrystalline quartz (SiO₂), chiefly chert/jasper with iron-oxide staining; mixed clasts may include quartzite and other silicates

AI-generated identification · may be incorrect

Typically Mohs hardness 6.5–7, dull to waxy or vitreous luster, opaque brown/red/yellow coloration, and no visible cleavage; the rounded surfaces indicate water abrasion. The white piece with brown circular marks appears to be a polished or weathered siliceous pebble, possibly chert or quartzite.

Identified August 16, 2026More sedimentary →

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At a glance

Common name: Mixed river gravel, prominently iron-stained chert/jasper
Scientific name: Microcrystalline quartz (SiO₂), chiefly chert/jasper with iron-oxide staining; mixed clasts may include quartzite and other silicates
Category: sedimentary
Identified: August 16, 2026
Method: Standard

AI Estimated Value

$1–$10 for ordinary mixed gravel; $10–$40 for attractive individual jasper/chert pieces, higher only if exceptional patterning or lapidary quality is confirmed.

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 water-rounded cobbles and pebbles eroded from older bedrock and deposited in a stream or gravel bar. Chert forms by silica replacement in sedimentary rocks, commonly during the Paleozoic–Cenozoic, while iron oxides create the red, orange, and brown colors.

Uses & applications

Used as decorative landscaping gravel, aggregate, lapidary material, and occasionally for cabochons or carvings. Attractive jasper and patterned chert have modest collector appeal.

Geological facts

Iron minerals such as hematite and goethite produce the rusty colors; banding, brecciation, or orbicular patterns can increase interest. The assortment is not a single uniform rock species.

Field identification & locations

Identify chert/jasper by its very fine grain, hardness, waxy fracture, and conchoidal edges; it should scratch glass but not be scratched by a steel knife. Common in stream gravels worldwide, including glacial and desert deposits.