mineral

Iron-stained Quartz (Gossan/Limonite-coated Quartz)

Silicon Dioxide (SiO2) with Hydrated Iron Oxides (FeO(OH)·nH2O)

Hardness: 7 (Quartz) and 4-5.5 (Limonite staining); Color: Rusty orange, yellow-brown, reddish; Luster: Vitreous to dull/earthy; Crystal structure: Trigonal/Hexagonal; Cleavage: None/Conchoidal fracture.

Hardness: 7 (Quartz) and 4-5
Color: Rusty orange, yellow-brown, reddish
Luster: Vitreous to dull/earthy

Identified March 1, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the secondary oxidation of iron-bearing sulfide minerals (like pyrite) within quartz veins. The iron oxides precipitate and stain the host quartz as groundwater reacts with minerals near the surface.

Uses & applications

Primarily used as an indicator for prospectors searching for gold or base metal deposits; industrial quartz used in glass and construction; minor decorative collecting.

Geological facts

This type of rock is often called 'gossan' or 'iron hat' by miners. Because iron sulfides frequently occur alongside gold, finding iron-stained quartz in the field is a classic sign of potential precious metal mineralization nearby.

Field identification & locations

Identify by its heavy orange/red staining and high hardness (it will scratch glass). Often found in hydrothermal vein systems and mining districts. Collectors should look for signs of 'honeycomb' texture within the iron staining which indicates leached sulfides.

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