metamorphic

Quartzite

Quartzite (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale. Color: white, grey, or yellowish. Luster: vitreous to dull. Crystal Structure: trigonal (granular). Cleavage: none. Specific Gravity: 2.6-2.7.

Hardness: 7 on Mohs scale
Color: white, grey, or yellowish
Luster: vitreous to dull

Identified May 26, 2026More metamorphic →

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Physical properties

Hardness: 7 on Mohs scale. Color: white, grey, or yellowish. Luster: vitreous to dull. Crystal Structure: trigonal (granular). Cleavage: none. Specific Gravity: 2.6-2.7.

Formation & geological history

Formed through the metamorphism of quartz-rich sandstone under high heat and pressure. This usually occurs during mountain-building events (orogenic processes).

Uses & applications

Used in construction as road ballast, roofing tiles, and decorative stone. Highly valued in high-purity form for glass making and silicon production.

Geological facts

Quartzite is so durable that it often survives intense weathering better than the rocks surrounding it, forming the caps of many mountain ridges.

Field identification & locations

Identify by its extreme hardness (cannot be scratched by steel) and lack of reaction to acid. It is commonly found in fold mountain belts globally. Collectors look for sugary textures.