metamorphic
Quartzite pebble
Quartzite (SiO2)
Hardness: 7 (Mohs scale); Color: Grayish-tan, translucent; Luster: Vitreous to waxy; Crystal structure: Hexagonal/trigonal (crypto-crystalline); Cleavage: Indistinct/Conchoidal fracture; Specific gravity: 2.6-2.7
- Hardness
- 7 (Mohs scale)
- Color
- Grayish-tan, translucent
- Luster
- Vitreous to waxy
Identified More metamorphic →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 (Mohs scale); Color: Grayish-tan, translucent; Luster: Vitreous to waxy; Crystal structure: Hexagonal/trigonal (crypto-crystalline); Cleavage: Indistinct/Conchoidal fracture; Specific gravity: 2.6-2.7
Formation & geological history
Formed from the metamorphism of quartz sandstone under intense heat and pressure. This particular specimen is a water-worn river stone, smoothed by fluvial erosion and transport.
Uses & applications
Used as decorative landscaping stone, in road construction (ballast), and occasionally as a source of high-purity silica for glassmaking. Smooth pebbles are popular for meditation stones and aquariums.
Geological facts
Quartzite is so tough that it often survives intense mechanical weathering that breaks down other rocks. It is harder than steel and will easily scratch a knife blade.
Field identification & locations
Identify in the field by its hardness (it scratches glass) and its smooth, rounded shape if found in riverbeds. It lack the visible grains found in sandstone because the quartz grains have recrystallized and fused together.
More like this
