mineral

Iron-stained milky quartz

Quartz (SiO₂), locally limonite/goethite-stained

AI-generated identification · may be incorrect

Typically Mohs hardness 7, white to honey-brown, vitreous to greasy luster, translucent edges, conchoidal fracture, and no cleavage; the dark patches are likely iron oxides or minor host-rock inclusions. Crystal structure is trigonal, though this specimen is massive rather than visibly crystalline.

Identified August 27, 2026More mineral →

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Physical properties

Formation & geological history

Formed when silica-rich hydrothermal fluids precipitated quartz in fractures or cavities, later acquiring yellow-brown iron-oxide staining through weathering. Exact age and locality cannot be determined from the image.

Uses & applications

Used as a durable silica source, aggregate, abrasives, and ornamental stone; attractive pieces are collected or cut and polished, but this specimen appears mainly lapidary/collecting grade.

Geological facts

Quartz is one of Earth’s most abundant minerals and commonly survives weathering because of its hardness and chemical resistance.

Field identification & locations

Identify by hardness—quartz scratches glass—combined with conchoidal fracture and lack of cleavage; iron staining produces the warm coloration. Common worldwide in veins, geodes, pegmatites, and quartz-rich rocks.