Mineral
Iron-stained Quartz (with Limonite/Hematite)
Silicon Dioxide (SiO2) with Iron Oxide inclusions (FeO(OH) or Fe2O3)
AI-generated identification · may be incorrectHardness: 7 (Mohs scale); Color: Rusty orange, brown, and tan over a white/clear base; Luster: Vitreous to dull/earthy; Crystal Structure: Trigonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.
- Hardness
- 7 (Mohs scale)
- Color
- Rusty orange, brown, and tan over a white/clear base
- Luster
- Vitreous to dull/earthy
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Physical properties
Hardness: 7 (Mohs scale); Color: Rusty orange, brown, and tan over a white/clear base; Luster: Vitreous to dull/earthy; Crystal Structure: Trigonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.
Formation & geological history
Formed in hydrothermal veins or as a secondary mineral precipitate in sedimentary environments. Iron staining occurs when groundwater rich in iron oxides permeates the host quartz. Ages vary from Precambrian to recent.
Uses & applications
Primarily of interest to mineral collectors or as an industrial source for iron/silica. Often treated with acid to clean the quartz for decorative use.
Geological facts
Commonly known by prospectors as 'iron hat' or 'gossan' when found in large outcrops, it is often a field indicator for deeper mineral deposits such as gold or copper.
Field identification & locations
Identify in the field by its high hardness (scratches glass), rust-colored staining that cannot be easily washed off, and lack of cleavage. Found globally in mountainous and mining regions.
