metamorphic
Quartzite Pebble
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: tan, grey, or off-white; Luster: vitreous to dull; Crystal structure: hexagonal (microcrystalline); Cleavage: none, breaks with conchoidal or irregular fracture; Specific gravity: 2.6-2.65
- Hardness
- 7 on Mohs scale
- Color
- tan, grey, or off-white
- Luster
- vitreous to dull
Identified More metamorphic →
Explore Quartzite Pebble in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 on Mohs scale; Color: tan, grey, or off-white; Luster: vitreous to dull; Crystal structure: hexagonal (microcrystalline); Cleavage: none, breaks with conchoidal or irregular fracture; Specific gravity: 2.6-2.65
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone subjected to high heat and pressure. This specific specimen has been further shaped and rounded by fluvial or glacial transport through water erosion over thousands of years.
Uses & applications
Used in construction as road ballast, crushed stone, and roofing granules. High-purity quartzite is used to produce silica sand for glassmaking and industrial abrasives.
Geological facts
Quartzite is one of the most durable and weather-resistant rocks on Earth's surface. It is harder than steel and will easily scratch glass. Many mountain ranges, like the Appalachians, contain ridges made of quartzite because it resists erosion better than surrounding rocks.
Field identification & locations
Identify in the field by its hardness (it should scratch glass) and its sugary, crystalline texture when freshly broken. To distinguish it from sandstone, look for fractures that break through the sand grains rather than around them. Found globally in riverbeds, beaches, and glaciated regions.
