metamorphic
Quartzite pebble
Quartzite (primarily SiO2)
Hardness: 7 (Mohs scale); Color: Grayish-white to light olive; Luster: Dull to vitreous; Crystal structure: Granoblastic/Non-foliated; Cleavage: None; Specific gravity: 2.6-2.7
- Hardness
- 7 (Mohs scale)
- Color
- Grayish-white to light olive
- Luster
- Dull to vitreous
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Physical properties
Hardness: 7 (Mohs scale); Color: Grayish-white to light olive; Luster: Dull to vitreous; Crystal structure: Granoblastic/Non-foliated; Cleavage: None; Specific gravity: 2.6-2.7
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure, causing quartz grains to recrystallize and fuse.
Uses & applications
Used as a decorative stone, in construction aggregates, and historically as a tool-making material due to its extreme durability.
Geological facts
Quartzite is so hard that it will scratch glass and even steel. When it breaks, the fracture passes through the quartz grains rather than around them, unlike its parent sandstone.
Field identification & locations
Look for a sugary texture and extreme hardness. Often found in riverbeds or coastal areas as rounded cobbles after being eroded from mountain ranges.
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