metamorphic
Quartzite
Quartzite (composed primarily of SiO2)
Hardness: 7 (Mohs scale), Color: White, gray, tan, or brown with a sugary texture, Luster: Vitreous to dull, Crystal Structure: Hexagonal (microcrystalline), Cleavage: None (conchoidal fracture)
Identified More metamorphic →
Explore Quartzite in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 (Mohs scale), Color: White, gray, tan, or brown with a sugary texture, Luster: Vitreous to dull, Crystal Structure: Hexagonal (microcrystalline), Cleavage: None (conchoidal fracture)
Formation & geological history
Formed through the regional or contact metamorphism of quartz starch-rich sandstone. High heat and pressure cause quartz grains to recrystallize and fuse together into a dense, hard rock.
Uses & applications
Used as a decorative stone in construction, road ballast, crushed stone for railways, and historically for stone tools due to its hardness and durability.
Geological facts
Quartzite is so tough that it usually breaks through the quartz grains themselves rather than around them, which distinguishes it from sandstone. Some varieties can be found in mountain ranges that were once ancient beach environments.
Field identification & locations
Identify in the field by its hardness (it scratches glass easily) and its sugary, crystalline appearance on a fresh break. Commonly found in folded mountain belts globally.
More like this
