mineral

Ferruginous Quartz

Silicon Dioxide (SiO2) with Hematite/Limonite impurities

Hardness: 7 (Mohs scale); Color: Milky white with reddish-brown/orange staining; Luster: Vitreous to greasy; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 (Mohs scale)
Color: Milky white with reddish-brown/orange staining
Luster: Vitreous to greasy

Identified March 21, 2026More mineral →

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Physical properties

Formation & geological history

Formed through hydrothermal processes where silica-rich fluids crystallize in veins or vugs. The reddish tint is caused by iron oxide (hematite or limonite) staining often introduced via groundwater during or after the quartz formation. Can range from Precambrian to recent ages.

Uses & applications

Primary source of silicon for electronics and glassmaking; commonly used as landscaping stone, in jewelry as 'Eisenkiesel', or as a collector's specimen for those studying mineral inclusions.

Geological facts

Commonly known as 'Iron-stained Quartz'. While pure quartz is clear, the presence of just a tiny percentage of iron can turn large rock faces bright red or orange. It is one of the most chemically stable minerals on Earth's surface.

Field identification & locations

Identify in the field by its inability to be scratched by steel, its waxy to glassy appearance, and the fact that the red color is often a surface coating or concentrated in cracks. Found globally in granite outcrops, mountains, and stream beds.

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