Mineral
Quartz (possibly milky quartz or quartz with inclusions)
SiO2 (Silicon Dioxide)
Hardness: 7 on Mohs scale. Color: Translucent to opaque white, gray, or colorless. Often appears milky due to microscopic fluid inclusions. Luster: Vitreous (glassy). Crystal Structure: Hexagonal (trigonal system), typically forming 6-sided prisms terminating in 6-sided pyramids. Cleavage: None (conchoidal fracture).…
- Hardness
- 7 on Mohs scale
- Color
- Translucent to opaque white, gray, or colorless
- Luster
- Vitreous (glassy)
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Physical properties
Hardness: 7 on Mohs scale. Color: Translucent to opaque white, gray, or colorless. Often appears milky due to microscopic fluid inclusions. Luster: Vitreous (glassy). Crystal Structure: Hexagonal (trigonal system), typically forming 6-sided prisms terminating in 6-sided pyramids. Cleavage: None (conchoidal fracture). Specific Gravity: 2.65.
Formation & geological history
Quartz is one of the most abundant minerals in the Earth's crust. It forms in a wide range of geological environments. It can crystallize from magma (igneous rocks like granite), precipitate from hydrothermal solutions (veins), and can also be found in metamorphic rocks (quartzite) and sedimentary rocks (sandstone). Its formation can span billions of years, from early Earth to present day.
Uses & applications
Industry: Used in electronics (oscillators, filters), optics (lenses, prisms), abrasives, and as a raw material in glass and ceramic production. Construction: A major component of sand and gravel used in concrete and asphalt. Jewelry: Many varieties of quartz (e.g., amethyst, citrine, rose quartz) are highly valued as gemstones. Milky quartz itself is less valued as a gemstone but is often cut into cabochons or beads.
Geological facts
Quartz is piezo-electric, meaning it generates an electric charge when subjected to mechanical stress, and vice versa. This property makes it essential in modern electronics for precise frequency control. It is also highly resistant to weathering, making it a prominent component of sands and soil.
Field identification & locations
To identify in the field: Look for its hardness (scratches glass, cannot be scratched by a steel knife), glassy luster, lack of cleavage, and conchoidal fracture. It often forms well-defined crystals, though in masses like the one pictured, it appears granular. It's commonly found in virtually all types of rocks and throughout the world. The specimen in the image has a somewhat milky appearance and possibly dark inclusions, which are typical for common quartz varieties.
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Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Schist
Schist
Metamorphic
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Nephrite Jade
Nephrite
Mineral/Rock
Granite
Granite (Phaneritic intrusive igneous rock)
igneous