metamorphic
Quartzite
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale. Color: Tan, yellow, or reddish due to iron oxide staining. Luster: Vitreous to dull. Crystal structure: Granular, interlocking quartz crystals. Cleavage: None (fractures across grains). Specific gravity: 2.6-2.7.
- Hardness
- 7 on Mohs scale
- Color
- Tan, yellow, or reddish due to iron oxide staining
- Luster
- Vitreous to dull
Identified More metamorphic →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 on Mohs scale. Color: Tan, yellow, or reddish due to iron oxide staining. Luster: Vitreous to dull. Crystal structure: Granular, interlocking quartz crystals. Cleavage: None (fractures across grains). Specific gravity: 2.6-2.7.
Formation & geological history
Formed through the metamorphism of quartz sandstone. Under high heat and pressure, quartz grains recrystallize and fuse together. Often associated with convergent plate boundaries and mountain-building events.
Uses & applications
Used in construction as road ballast, crushed stone, and decorative building stone. High-purity quartzite is used to produce silica sand for glassmaking and industrial abrasives.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rock during erosion, frequently forming the peaks of ridges and mountains. It is significantly harder than the sandstone it originates from.
Field identification & locations
Identify in the field by its extreme hardness (cannot be scratched by a steel knife) and the way it fractures through the sand grains rather than around them. Common in metamorphic terrains worldwide.
More like this
