metamorphic
Quartzite
Metamorphic Quartzite (primarily SiO2)
Hardness: 7 on the Mohs scale. Color: White, gray, or weathered shades with moss growth. Luster: Vitreous to greasy. Crystal structure: Interlocking quartz grains (non-foliated). Cleavage: None, breaks across grains (conchoidal fracture). Specific gravity: 2.65.
- Hardness
- 7 on the Mohs scale
- Color
- White, gray, or weathered shades with moss growth
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 7 on the Mohs scale. Color: White, gray, or weathered shades with moss growth. Luster: Vitreous to greasy. Crystal structure: Interlocking quartz grains (non-foliated). Cleavage: None, breaks across grains (conchoidal fracture). Specific gravity: 2.65.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone or chert under high temperature and tectonic pressure. Geological age varies widely depending on the formation region, spanning from Precambrian to Cenozoic eras.
Uses & applications
Used in construction, road aggregate, railway ballast, manufacturing of silica brick, and sometimes as a decorative stone or countertop material due to its high durability.
Geological facts
Pure quartzite is one of the most chemically inert and physically durable rocks on Earth's surface, highly resistant to weathering, which explains why it often forms prominent ridges.
Field identification & locations
Identified in the field by its extreme hardness (scratches glass easily), lack of significant reaction to acid, and sugary textured interlocking crystals visible on fresh fracture surfaces. Common worldwide in ancient mountain belts.
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