metamorphic
Quartzite
Quartzite (Primary mineral: SiO2)
Hardness: 7 on Mohs scale; Color: Tan, white, or light grey (due to beach weathering); Luster: Vitreous to dull; Crystal structure: Non-foliated granoblastic; Cleavage: None (fractures conchoidally); Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Tan, white, or light grey (due to beach weathering)
- 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, white, or light grey (due to beach weathering); Luster: Vitreous to dull; Crystal structure: Non-foliated granoblastic; Cleavage: None (fractures conchoidally); Specific gravity: 2.6-2.7
Formation & geological history
Formed through the regional metamorphism of quartz sandstone. High heat and pressure cause the original quartz grains to recrystallize and fuse together. These specimens are often millions of years old and become rounded through coastal wave action (beach tumble).
Uses & applications
Industrial use as crushed stone for road ballast, a source of silica for glassmaking, and frequently used in lapidary for polished river/beach stones and tumbled decorative landscaping.
Geological facts
Quartzite is so hard and chemically resistant that it often survives as large boulders or rounded cobbles long after the surrounding softer rocks have eroded away. It is tougher than the sandstone it originated from.
Field identification & locations
Identify it by its inability to be scratched by a steel knife (unlike limestone) and its sugary/crystalline texture when broken. Commonly found on beaches and in riverbeds globally. Collectors look for unique colors or translucent qualities.
More like this
