metamorphic
Iron-rich quartzite or ironstone
Ferruginous quartzite, likely quartz (SiO₂) with hematite/goethite (Fe₂O₃/FeO(OH))
AI-generated identification · may be incorrectHardness approximately 6–7 (quartz-rich areas), with rusty red-brown, yellow-brown, and gray coloration; generally dull to granular, with local earthy or weakly metallic iron-oxide luster. Massive, fine- to medium-grained texture; no obvious cleavage, and high specific gravity where iron-rich.
Identified More metamorphic →
Explore Iron-rich quartzite or ironstone in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness approximately 6–7 (quartz-rich areas), with rusty red-brown, yellow-brown, and gray coloration; generally dull to granular, with local earthy or weakly metallic iron-oxide luster. Massive, fine- to medium-grained texture; no obvious cleavage, and high specific gravity where iron-rich.
Formation & geological history
Likely formed when quartz-rich sediment was metamorphosed and impregnated or cemented by iron oxides; oxidation commonly produces the rust-colored surface. Exact geological age and locality cannot be determined from the photograph alone.
Uses & applications
Primarily a collector specimen or educational sample; iron-rich varieties may be considered low-grade iron ore, but this piece is unlikely to have commercial value without assay.
Geological facts
The reddish-brown colors commonly come from hematite, while yellow-orange coatings often indicate goethite or limonite. A streak test and magnet test can help distinguish iron-rich rock from ordinary quartzite.
Field identification & locations
Common in banded-iron formations, weathered iron deposits, and metamorphic terrains worldwide. Test an inconspicuous area: quartz scratches glass, hematite leaves a red-brown streak, and magnetite causes a strong magnet response.
More like this
