mineral

Iron-stained quartz (likely milky quartz)

Quartz, SiO₂, with limonite/goethite surface staining

AI-generated identification · may be incorrect

Hardness 7 Mohs; translucent gray-white to honey-brown, vitreous to dull luster, no obvious cleavage, conchoidal fracture, and typically specific gravity near 2.65. The rusty coating is iron-oxide staining; the rounded shape suggests natural abrasion or weathering.

Identified September 1, 2026More mineral →

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Physical properties

Formation & geological history

Quartz commonly crystallizes from silica-rich hydrothermal fluids or occurs in veins and quartz-rich rocks; later weathering deposits limonite/goethite on its surface. Quartz is geologically widespread, forming from Precambrian to modern environments.

Uses & applications

Quartz is used in glass, ceramics, abrasives, electronics, and construction aggregate. This small stained piece has mainly educational or modest collecting value rather than gem value.

Geological facts

A steel knife should not scratch it, while quartz should scratch ordinary glass. The brown color is probably not a separate quartz variety such as smoky quartz, but an iron-rich surface film.

Field identification & locations

Common in quartz veins, stream gravels, and weathered crystalline terrains, including parts of central Nigeria near 8.5°N, 8.5°E. Confirm by testing hardness and checking for conchoidal fracture; acid reaction should be absent.