Quartzite with Chlorite

Physical Properties

Hardness: 7 on Mohs scale; Color: White to light green/grey; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal (granular); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7

Formation & Geological History

Formed through the regional metamorphism of quartz-rich sandstone. High heat and pressure cause the quartz grains to recrystallize and fuse together, while the green tint suggests the presence of chlorite minerals formed during low-grade metamorphism.

Uses & Applications

Used in construction as crushed stone or road ballast, as decorative stone in landscaping, or as a source of silica in glass manufacturing.

Geological Facts

Quartzite is so tough that it often breaks through the individual quartz grains rather than around them, which distinguishes it from sandstone. The green hue often indicates it was formed in a 'greenschist' metamorphic facies environment.

Field Identification & Locations

Identify in the field by its extreme hardness (it will easily scratch glass and steel) and its granular, sugary texture. Common in ancient mountain belts and shield areas like the Appalachians or the Canadian Shield.

Identified on: 4/14/2026

Mode: Standard