metamorphic
Iron-rich quartzite or silicified ironstone
Ferruginous quartzite; chiefly microcrystalline quartz (SiO₂) with iron oxides/hydroxides such as hematite and goethite
AI-generated identification · may be incorrectHardness about 6.5–7 (quartz), brown to reddish-black with rusty iron staining, dull to slightly vitreous luster, massive granular texture, and no obvious cleavage; likely high specific gravity from iron minerals.
Identified More metamorphic →
Explore Iron-rich quartzite or silicified ironstone in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness about 6.5–7 (quartz), brown to reddish-black with rusty iron staining, dull to slightly vitreous luster, massive granular texture, and no obvious cleavage; likely high specific gravity from iron minerals.
Formation & geological history
Formed when quartz-rich sandstone was metamorphosed and cemented, with later oxidation adding iron staining. Precise age and locality cannot be determined from the photograph; such rocks range from Precambrian to younger terrains.
Uses & applications
Primarily a field specimen or decorative stone; dense ferruginous varieties may be used locally as aggregate or building stone, but this example has limited commercial value.
Geological facts
The dark metallic-looking areas may be hematite or magnetite, while orange-brown surfaces commonly indicate goethite or limonite weathering.
Field identification & locations
Identify by its exceptional hardness, quartz-rich granular fracture, rusty streaking, and possible weak magnetism if magnetite is present; common in metamorphic belts, iron formations, and weathered quartz veins.
More like this
