igneous
Iron-rich river pebble, likely weathered basalt or ironstone
Probable basalt (plagioclase–pyroxene rock) with iron-oxide/hydroxide weathering; exact identification requires testing
AI-generated identification · may be incorrectDark brown to black, dull to weakly metallic earthy luster, fine-grained and rounded from abrasion; likely Mohs hardness 5–6, with no visible cleavage. The rusty color suggests hematite/goethite staining; apparent pits may be vesicles or weathering cavities.
Identified More igneous →
Explore Iron-rich river pebble, likely weathered basalt or ironstone in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Dark brown to black, dull to weakly metallic earthy luster, fine-grained and rounded from abrasion; likely Mohs hardness 5–6, with no visible cleavage. The rusty color suggests hematite/goethite staining; apparent pits may be vesicles or weathering cavities.
Formation & geological history
Most likely an ancient mafic volcanic rock formed when basaltic lava cooled rapidly, then chemically weathered and rounded in a stream or shoreline. Its precise geological age and setting cannot be determined from the photograph.
Uses & applications
Common specimens have little commercial value; basalt is widely used as crushed aggregate, roadstone, riprap, and occasionally building stone. Iron-rich varieties may interest beginning collectors but are not normally gem material.
Geological facts
Basalt commonly contains microscopic plagioclase and pyroxene crystals, so it can look uniformly smooth even under magnification. A strong response to a magnet would indicate abundant magnetite, while a red-brown streak points toward hematite.
Field identification & locations
Likely locations include volcanic terrains and gravel deposits worldwide; inspect a fresh chip for a dark gray fine-grained interior and test streak, hardness, density, and magnetism. Estimated value: $1–$10 for an ordinary pebble, or roughly $10–$30 if unusually attractive or locality-labeled.
