Quartzite

Hardness: 7 (Mohs scale), Color: Pinkish-purple to reddish-brown (due to iron oxide), Luster: Dull to vitreous, Texture: Granular, sugary appearance, Structure: Non-foliated massive rock from recrystallized quartz grains.

Formed through the regional metamorphism of quartz-rich sandstone. High heat and pressure cause quartz grains to recrystallize and fuse together, creating an extremely durable rock. Primarily dates from various eras, frequently Proterozoic.

Used in construction as crushed stone for road ballast, building material, and occasionally as a decorative stone in landscaping or as a refractory material due to its high heat resistance.

Quartzite is so hard and dense that when broken, it fractures through the quartz grains rather than along their boundaries, unlike its parent sandstone. It is extremely resistant to chemical weathering.

Identify in the field by its hardness (will scratch glass easily) and granular texture. Look for pinkish or purple hues indicating hematite content. It often forms prominent ridges or cliffs because it resists erosion better than surrounding rocks.