metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: typically white to gray, may have yellow or green tints; Luster: Vitreous to dull; Crystal structure: Trigonal; Fracture: Conchoidal to uneven; Specific Gravity: 2.65.
- Hardness
- 7 on Mohs scale
- Color
- typically white to gray, may have yellow or green tints
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: typically white to gray, may have yellow or green tints; Luster: Vitreous to dull; Crystal structure: Trigonal; Fracture: Conchoidal to uneven; Specific Gravity: 2.65.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone. High heat and pressure cause the quartz grains to recrystallize and fuse together, creating a hard, dense rock.
Uses & applications
Used extensively in road construction as ballast or aggregate, as a decorative stone in landscaping, and sometimes in the manufacturing of glass or ceramics if high purity quartz is present.
Geological facts
Quartzite is so hard that it will scratch glass and is more durable than many other common rocks like limestone or sandstone. Because of its resistance to weathering, it often forms prominent ridges and hills.
Field identification & locations
Identify in the field by its grainy, sugary texture and extreme hardness (cannot be scratched by a steel blade). It is commonly found in mountainous regions or ancient shield areas where tectonic activity has occurred.
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