mineral
Quartz
Silicon Dioxide (SiO2)
Hardness: 7 on Mohs scale; Color: White to translucent; Luster: Vitreous to waxy (when weathered); Crystal Structure: Hexagonal (trigonal); Cleavage: Indistinct/Conchoidal fracture; Specific Gravity: 2.65
- Hardness
- 7 on Mohs scale
- Color
- White to translucent
- Luster
- Vitreous to waxy (when weathered)
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Physical properties
Hardness: 7 on Mohs scale; Color: White to translucent; Luster: Vitreous to waxy (when weathered); Crystal Structure: Hexagonal (trigonal); Cleavage: Indistinct/Conchoidal fracture; Specific Gravity: 2.65
Formation & geological history
Formed through the cooling of silica-rich magma or from hydrothermal solutions. It is found in all rock types (igneous, metamorphic, and sedimentary) across all geological ages.
Uses & applications
Used extensively in construction (sand/aggregate), glassmaking, electronics (piezoelectric properties), and as a gemstone or decorative collector's piece.
Geological facts
Quartz is one of the most abundant minerals in the Earth's continental crust. It is highly resistant to chemical and physical weathering, which is why it often remains as pebbles in rivers and on beaches.
Field identification & locations
Identify by its hardness (will scratch glass) and lack of cleavage. This specimen appears to be a river-worn or weathered quartz cobble. Common in riverbeds, gravel pits, and mountain ranges worldwide.
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Other mineral specimens
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Sandstone with Mineral Veining or Crust
Sedimentary Sandstone (mostly SiO2 with Fe2O3 tinting)
sedimentary
Schist
Schist
Metamorphic
Potassium Feldspar (Orthoclase)
Orthoclase (KAlSi3O8)
mineral
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic