metamorphic
Quartzite with inclusions
Quartzite (SiO2)
Hardness: 7 (Mohs scale), Color: Dirty gray to brownish with translucent patches, Luster: Vitreous to dull, Structure: Granofelsic / non-foliated, Cleavage: None (conchoidal fracture typical of quartz components).
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Physical properties
Hardness: 7 (Mohs scale), Color: Dirty gray to brownish with translucent patches, Luster: Vitreous to dull, Structure: Granofelsic / non-foliated, Cleavage: None (conchoidal fracture typical of quartz components).
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone. High heat and pressure cause the original sand grains to recrystallize into a dense network of interlocking crystals.
Uses & applications
Primarily used as a decorative stone, in construction as road ballast, or for high-silica industrial processes. Hand specimens are mostly for educational or amateur collecting.
Geological facts
Quartzite is so tough that it often survives intense weathering better than other rocks. It is frequently mistaken for sandstone, but unlike sandstone, it will break through the grains rather than around them.
Field identification & locations
Identify by its extreme hardness (cannot be scratched by steel) and lack of reaction to acid. Often found in mountainous regions or ancient sedimentary basins. This specimen specifically shows a grainy, weathered exterior.
