mineral

Iron-stained quartz-bearing rock

Quartz (SiO₂), likely in a limonite/goethite-rich matrix

AI-generated identification · may be incorrect

Gray to brown, opaque-to-translucent silica with earthy yellow-brown iron-oxide coatings; vitreous to dull luster, irregular fracture, no obvious cleavage, and Mohs hardness about 7 for quartz (so it can scratch glass).

Identified August 8, 2026More mineral →

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Physical properties

Formation & geological history

Likely formed by hydrothermal or groundwater silica deposition followed by weathering and oxidation of iron-bearing minerals; the exact geological age cannot be determined from the photograph.

Uses & applications

Primarily a collector specimen; quartz-rich material may be used as aggregate or silica source, though this irregular iron-stained piece has little industrial value and is not gem quality.

Geological facts

The brown coloration commonly results from goethite and limonite coatings or inclusions. Metallic-looking patches may be iron oxides rather than native metal.

Field identification & locations

Test a fresh edge for glass-scratching hardness and inspect for quartz’s conchoidal fracture; a streak test may show a yellow-brown to reddish-brown streak from iron oxides. Common in weathered veins, gossans, and hydrothermal districts worldwide.