mineral

Iron-stained quartz with possible feldspar

Quartz (SiO₂), likely with limonite/goethite staining and feldspar matrix

AI-generated identification · may be incorrect

White to translucent, vitreous quartz with a rusty yellow-brown iron-oxide coating; quartz hardness 7, no cleavage, conchoidal fracture, hexagonal crystal structure, and specific gravity about 2.65. The rough, granular matrix may include feldspar or other silicates.

Identified August 18, 2026More mineral →

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Physical properties

Formation & geological history

Likely formed in a hydrothermal vein or pegmatitic cavity, where quartz crystallized from mineral-rich fluids and was later stained by oxidation of iron-bearing minerals. Precise age and locality cannot be determined from the photograph.

Uses & applications

Common quartz is used in glass, ceramics, electronics, abrasives, and construction aggregate; attractive crystals are sold as inexpensive specimens. This piece has modest decorative or educational value.

Geological facts

The brown coloration is probably limonite/goethite rather than an intrinsic quartz color. A streak, hardness, and acid test would help distinguish the matrix minerals.

Field identification & locations

Look for glassy luster, lack of cleavage, and inability to scratch with a steel knife; quartz should scratch glass. Common worldwide in veins, cavities, pegmatites, and weathered rock.