metamorphic

Quartzite

Quartzite (primarily SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: typically white, gray, or tan but can be reddish due to iron; Luster: vitreous to matte; Structure: granoblastic/non-foliated; Cleavage: none.

Hardness: 7 on Mohs scale
Color: typically white, gray, or tan but can be reddish due to iron
Luster: vitreous to matte

Identified May 9, 2026More metamorphic →

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Physical properties

Hardness: 7 on Mohs scale; Color: typically white, gray, or tan but can be reddish due to iron; Luster: vitreous to matte; Structure: granoblastic/non-foliated; Cleavage: none.

Formation & geological history

Formed through the regional metamorphism of quartz-rich sandstone under intense heat and pressure. The individual quartz grains recrystallize and fuse together into a dense, hard mass.

Uses & applications

Used widely in road construction (crushed stone), as a decorative stone in architecture, for countertops, and as railway ballast due to its durability.

Geological facts

Quartzite is so hard and chemically resistant that it often stands out as high ridges or mountains because it erodes much more slowly than the surrounding rock layers.

Field identification & locations

Identify in the field by its extreme hardness (will scratch glass and steel) and sugary, crystalline texture. Found globally in ancient mountain belts and shield areas.