mineral
Milky Quartz Pebble
Crystalline Silicon Dioxide (SiO2)
Hardness: 7 on Mohs scale; Color: Opaque white to light gray; Luster: Vitreous to greasy; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
- Hardness
- 7 on Mohs scale
- Color
- Opaque white to light gray
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 7 on Mohs scale; Color: Opaque white to light gray; Luster: Vitreous to greasy; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
Formation & geological history
Formed from hydrothermal solutions or within igneous pegmatites. This specific specimen is a water-worn river pebble, likely millions of years old, weathered and transported by water action.
Uses & applications
Commonly used as a decorative ground cover, in construction aggregate, and as a source of silica for glass manufacturing and electronics.
Geological facts
Quartz is the second most abundant mineral in Earth's continental crust. The 'milky' appearance is caused by tiny inclusions of gas or liquid trapped during crystal growth.
Field identification & locations
Identify in the field by its hardness (it will scratch glass), its lack of cleavage, and its characteristic waxy or glassy luster. This type of pebble is ubiquitous in stream beds and glacial deposits.
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