mineral

Iron-stained quartz

Quartz (SiO₂), likely limonite/goethite-coated

AI-generated identification · may be incorrect

Hardness 7 Mohs; translucent to transparent with honey-brown to rusty staining, vitreous luster, and irregular fracture. Quartz is trigonal and lacks cleavage; the brown coating is earthy and opaque.

Identified September 18, 2026More mineral →

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Physical properties

Hardness 7 Mohs; translucent to transparent with honey-brown to rusty staining, vitreous luster, and irregular fracture. Quartz is trigonal and lacks cleavage; the brown coating is earthy and opaque.

Formation & geological history

Formed when silica-rich fluids deposited quartz in fractures or cavities, later acquiring iron-oxide staining during weathering and oxidation. The specimen’s precise geological age cannot be determined from the image.

Uses & applications

Used for glass, abrasives, electronics, and ornamental specimens; attractive transparent pieces may be cut or polished, though this rough piece is mainly a collector specimen.

Geological facts

The brown color is probably limonite/goethite rather than the quartz itself. Quartz can scratch ordinary glass and commonly shows conchoidal fracture.

Field identification & locations

Common in hydrothermal veins, quartz vugs, weathered ore zones, and gravel deposits worldwide. Confirm with a glass-scratch test and lack of cleavage; acid reaction would suggest calcite instead.