metamorphic
Quartzite River Rock
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Tan to light brown (due to iron oxide staining); Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.6 - 2.7
- Hardness
- 7 on Mohs scale
- Color
- Tan to light brown (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 to light brown (due to iron oxide staining); Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.6 - 2.7
Formation & geological history
Formed from the metamorphism of quartz sandstone under intense heat and pressure. This specific specimen shows signs of mechanical weathering and rounding as a result of transport in a high-energy water environment (river or stream).
Uses & applications
Commonly used as durable construction aggregate, road ballast, and decorative garden stone. Pure quartzite is sometimes used as a source for silica in glassmaking.
Geological facts
Quartzite is so hard that it will scratch glass and even high-quality steel tools. Unlike sandstone, which breaks between grains, quartzite breaks through the quartz grains because they have been fused together.
Field identification & locations
Identify in the field by its hardness (cannot be scratched by a knife) and its grainy, 'sugary' texture hidden under its smooth, water-worn surface. Commonly found in riverbeds and glacial deposits. For collectors, these are often tumbler-ready.
More like this
