sedimentary
Limonite-stained Gossan/Ironstone
Goethite and Hematite (Fe2O3 • nH2O)
Hardness: 4-5.5 (variable); Color: Dark brown to metallic gray with yellowish-orange oxidation; Luster: Sub-metallic to dull; Structure: Masses or crusts; Cleavage: None
- Hardness
- 4-5
- Color
- Dark brown to metallic gray with yellowish-orange oxidation
- Luster
- Sub-metallic to dull
Identified More sedimentary →
Explore Limonite-stained Gossan/Ironstone in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 4-5.5 (variable); Color: Dark brown to metallic gray with yellowish-orange oxidation; Luster: Sub-metallic to dull; Structure: Masses or crusts; Cleavage: None
Formation & geological history
Formed through the intensive chemical weathering and oxidation of iron-rich sulfide minerals or other iron-bearing rocks, often indicating a subsurface ore deposit.
Uses & applications
Historically used as a low-grade iron ore; currently used as a geological indicator for prospecting metal deposits and as a source of pigments (ochre).
Geological facts
Gossans are known as 'iron hats' to miners because they sit over the top of unoxidized ore bodies and were used since antiquity to find copper, gold, and silver.
Field identification & locations
Identifiable by its heavy weight relative to surrounding rocks and its distinct rusty-yellow or orange-brown staining. Found in mining districts and areas with high metal sulfide mineralization.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Cone-in-cone structure (Limestone)
Cone-in-cone structure (Secondary Sedimentary Structure)
sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone Grain
Clastic Sedimentary Rock Grain (SiO2 dominated)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary