Quartzite with inclusions

Physical Properties

Hardness: 7 on Mohs scale; Color: Tan to light brown with a dark grey/black mineral vein; Luster: Vitreous to dull; Crystal structure: Non-foliated, interlocking quartz grains; Cleavage: None (conchoidal fracture).

Formation & Geological History

Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, typically during mountain-building events. The dark band represents a concentrated mineral inclusion or a relict bedding plane from the original sedimentary rock.

Uses & Applications

Used primarily as crushed stone for road construction, railway ballast, and occasionally as decorative stone or flooring due to its high durability and resistance to weathering.

Geological Facts

Quartzite is so hard and chemically resistant that it often forms the ridges and peaks of mountain ranges because it weathers much more slowly than surrounding rocks.

Field Identification & Locations

Identify in the field by its inability to be scratched by steel, its sugary texture on fresh breaks, and its tendency to break across sand grains rather than around them. Found globally in ancient metamorphic terranes.

Identified on: 5/3/2026

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