mineral
Quartz (Iron-stained)
Silicon Dioxide (SiO2) with Iron Oxide inclusions
Hardness: 7 on Mohs scale; Color: Milky white with reddish-orange iron staining; Luster: Vitreous to greasy; Crystal Structure: Trigonal (Hexagonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
- Hardness
- 7 on Mohs scale
- Color
- Milky white with reddish-orange iron staining
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 7 on Mohs scale; Color: Milky white with reddish-orange iron staining; Luster: Vitreous to greasy; Crystal Structure: Trigonal (Hexagonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
Formation & geological history
Quartz forms in a wide variety of environments, most commonly from the cooling of magma or precipitation from hydrothermal veins. The iron staining occurs when the specimen is exposed to groundwater rich in iron oxides, causing surface discoloration or infilling into cracks.
Uses & applications
Used in glassmaking, electronics (piezoelectric properties), abrasives, and as a collector specimen. Iron-stained varieties can also be used as landscaping stone.
Geological facts
Quartz is the second most abundant mineral in Earth's continental crust. Its name comes from the German word 'Quarz', which has Slavic origins meaning 'hard'. It is highly resistant to both chemical and physical weathering.
Field identification & locations
Identify in the field by its hardness (it will scratch glass), its lack of cleavage, and its characteristic conchoidal (glass-like) fracture. It is ubiquitous globally and frequently found in gravel pits, stream beds, and mountainous regions.
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