mineral
Quartz and Iron Oxide
Quartz (Silicon Dioxide, SiO2) with possible Limonite/Hematite inclusions
Hardness: 7 on Mohs scale; Color: Clear to brownish-orange; Luster: Vitreous to dull; Crystal structure: Trigonal (hexagonal prisms); Cleavage: None/Conchoidal fracture; Specific gravity: 2.65.
- Hardness
- 7 on Mohs scale
- Color
- Clear to brownish-orange
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Clear to brownish-orange; Luster: Vitreous to dull; Crystal structure: Trigonal (hexagonal prisms); Cleavage: None/Conchoidal fracture; Specific gravity: 2.65.
Formation & geological history
Formed in hydrothermal veins or as a secondary mineral in volcanic cavities. The iron staining (brownish-orange) occurs when iron-bearing groundwaters react with oxygen on the crystal surfaces.
Uses & applications
Informational/educational specimen, decorative rock collecting, and industrial use for abrasives and silicon production.
Geological facts
Quartz is the second most abundant mineral in Earth's continental crust. Iron-stained quartz like this is common in areas where rust-forming minerals are present in the surrounding soil or rock matrix.
Field identification & locations
Identify in the field by its hardness (it will scratch glass and metal) and its crystal habit. Found globally in almost all geological environments including mountains, river beds, and deserts.
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