igneous
Weathered iron-rich basalt or volcanic scoria
Altered basalt, likely limonite/goethite-bearing (tentative)
AI-generated identification · may be incorrectDark brown to rusty orange, rough and highly weathered, with abundant irregular cavities or vesicles. Likely Mohs 5–6 where fresh; dull to earthy luster, fine-grained volcanic groundmass, and no obvious cleavage. The orange-brown coloration indicates iron-oxide/hydroxide staining.
Identified More igneous →
Explore Weathered iron-rich basalt or volcanic scoria in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Dark brown to rusty orange, rough and highly weathered, with abundant irregular cavities or vesicles. Likely Mohs 5–6 where fresh; dull to earthy luster, fine-grained volcanic groundmass, and no obvious cleavage. The orange-brown coloration indicates iron-oxide/hydroxide staining.
Formation & geological history
Probably a mafic volcanic rock altered by groundwater and surface weathering; its exact age cannot be determined from the photograph. Near 46.2°N, 123.0°W, weathered Columbia River Basalt or a related volcanic cobble is geologically plausible.
Uses & applications
Usually a common field specimen with little market value; occasionally used as landscaping stone or collected as an example of weathered volcanic rock.
Geological facts
The cavities may be original gas bubbles (vesicles), later enlarged by weathering or partly filled with secondary minerals. It does not show the metallic appearance expected of most iron meteorites.
Field identification & locations
Look for a dark gray, dense interior beneath the rusty rind, possible weak attraction to a magnet, and a streak that is generally pale gray rather than bright red. A fresh broken surface, magnet test, streak test, and specific-gravity measurement would improve identification; it could also be an iron-stained vesicular basalt or weathered industrial slag.
