mineral

Ferruginous Quartz

Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3) inclusions

Hardness: 7 (Mohs scale); Color: Orange, brownish-yellow, or rust; Luster: Vitreous to greasy; Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 (Mohs scale)
Color: Orange, brownish-yellow, or rust
Luster: Vitreous to greasy

Identified April 12, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale); Color: Orange, brownish-yellow, or rust; Luster: Vitreous to greasy; Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Formation & geological history

Formed in hydrothermal veins or pegmatites where silica-rich fluids cool and crystallize. The orange/brown tint is caused by iron staining or hematite/limonite inclusions during or after growth.

Uses & applications

Commonly used in lapidary work as a decorative stone, landscaping, and by mineral collectors for its unique coloration.

Geological facts

Also known as 'Eisenkiesel' in some regions, it is a variety of quartz where the iron content is high enough to change the mineral's color from transparent to opaque orange or reddish-brown.

Field identification & locations

Identify in the field by its hardness (scratches glass), waxy/glassy luster, and lack of cleavage. It is found globally in areas with high quartz and iron content in the soil or bedrock.

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