Mineral / Metamorphic
Quartz / Quartzite
Silicon Dioxide (SiO2)
Hardness: 7 on Mohs scale (scratches glass); Color: Off-white, tan, or milky-gray; Luster: Vitreous to dull; Crystal structure: Trigonal (often appears massive or granular in small fragments); Cleavage: None (conchoidal fracture).
- Hardness
- 7 on Mohs scale (scratches glass)
- Color
- Off-white, tan, or milky-gray
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale (scratches glass); Color: Off-white, tan, or milky-gray; Luster: Vitreous to dull; Crystal structure: Trigonal (often appears massive or granular in small fragments); Cleavage: None (conchoidal fracture).
Formation & geological history
Formed through the crystallization of silica-rich magma or via the metamorphism of quartz-rich sandstone. These specimens are ubiquitous across almost all geological ages due to the stability of silica.
Uses & applications
Used widely in construction as aggregate, in the glass-making industry, as an abrasive, and in electronics for its piezoelectric properties. This specific rough fragment is common for decorative landscaping or minor educational collections.
Geological facts
Quartz is the second most abundant mineral in Earth's continental crust. It is extremely resistant to weathering, which is why it often remains as small pebbles or fragments while other minerals break down into clay.
Field identification & locations
Identify in the field by its hardness (will not be scratched by a steel knife) and its inability to react with acid (unlike limestone). Common in riverbeds, deserts, and mountain ranges globally. Small pieces are excellent for teaching basic mineral hardness.
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