mineral

Ferruginous Quartz

Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3/FeO(OH)) inclusions

Hardness: 7 on Mohs scale; Color: Milky white to tan with orange, reddish-brown, or yellow iron staining; Luster: Vitreous (glassy) to waxy; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65.

Hardness: 7 on Mohs scale
Luster: Vitreous (glassy) to waxy

Identified March 21, 2026More mineral →

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Physical properties

Formation & geological history

Formed from silica-rich hydrothermal fluids or within pegmatites. The orange staining occurs during or after formation when iron-rich groundwater permeates cracks or coats the surface of the quartz. This process can occur across a vast range of geological ages from Precambrian to recent.

Uses & applications

Used primarily as decorative garden stone, in landscaping, or for lapidary work (tumbling and cabochons). Industrial grade quartz is used in glassmaking and electronics, though stained specimens are usually relegated to lower-tier aggregate or collector status.

Geological facts

Also known as 'Iron-stained Quartz' or 'Hematoid Quartz.' The iron oxide acts as a natural pigment; if the iron is included inside the crystal during growth, it is called hematoid quartz, whereas surface staining like this specimen is often just called 'ferruginous.'

Field identification & locations

Identify in the field by its hardness (will scratch glass and steel), lack of cleavage, and the characteristic rusty-orange staining that cannot be easily washed off with water. Commonly found in riverbeds, mountain scree, and gravel pits globally.

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