mineral
Quartz (Iron-stained)
Silicon Dioxide (SiO2)
Hardness: 7 (Mohs scale); Color: Clear to yellowish-brown (due to iron oxide staining); Luster: Vitreous to greasy; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture)
- Hardness
- 7 (Mohs scale)
- Color
- Clear to yellowish-brown (due to iron oxide staining)
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 7 (Mohs scale); Color: Clear to yellowish-brown (due to iron oxide staining); Luster: Vitreous to greasy; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture)
Formation & geological history
Formed in various environments, most commonly from hydrothermal veins and pegmatites. This specimen likely weathered out of a quartz vein or river bed, acquiring iron staining from groundwater.
Uses & applications
Industrial use in glass and ceramics; electronics; widely used in jewelry (as citrine or smoky quartz variants) and gemstone collecting.
Geological facts
Quartz is the second most abundant mineral in the Earth's continental crust. Specimens that are yellow/brown naturally are often called citrine, but surface staining from iron oxides is common in raw field samples.
Field identification & locations
Identify in the field by its hardness (scratches glass) and lack of cleavage. Commonly found in riverbeds, mountains, and desert pavement worldwide.
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