igneous
Iron-stained volcanic breccia
Likely andesite or basaltic breccia with limonite/goethite staining
AI-generated identification · may be incorrectDark gray, fine-grained angular volcanic fragments cemented together, with orange-brown iron-oxide coatings and veins; typically hardness 5–6, dull to slightly waxy luster, no obvious cleavage, and specific gravity about 2.6–3.0.
Identified More igneous →
Explore Iron-stained volcanic breccia in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Dark gray, fine-grained angular volcanic fragments cemented together, with orange-brown iron-oxide coatings and veins; typically hardness 5–6, dull to slightly waxy luster, no obvious cleavage, and specific gravity about 2.6–3.0.
Formation & geological history
Formed when volcanic rock fragments accumulated and were lithified, commonly in explosive volcanic or fault-zone settings; iron-bearing fluids later oxidized to limonite/goethite. Exact age and composition require thin-section or geochemical testing.
Uses & applications
Primarily a geological or lapidary specimen; locally used as decorative stone or aggregate if sound, but its irregular fracturing limits construction applications.
Geological facts
The orange material is probably hydrated iron oxide rather than native copper or gold. A magnet, streak test, acid test, and fresh-break examination can help distinguish altered basaltic breccia from iron-rich jasper or mineralized fault rock.
Field identification & locations
Look for angular clasts, volcanic texture, and rusty coatings; common in volcanic belts and hydrothermal zones worldwide. Value is generally about $5–$30 for an ordinary hand specimen, or $30–$100 if unusually attractive or locality-documented.
