metamorphic
Quartzite pebble
Crystalline silica (SiO2)
Hardness: 7 (Mohs scale), Color: Dirty white to brownish-grey, Luster: Vitreous to dull, Crystal structure: Hexagonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
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Physical properties
Hardness: 7 (Mohs scale), Color: Dirty white to brownish-grey, Luster: Vitreous to dull, Crystal structure: Hexagonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure. This specific piece shows signs of environmental weathering and river rounding, likely from the Quaternary period.
Uses & applications
Largely used as a source of silica in glass manufacturing, as construction aggregate, or in road ballast. Low-grade specimens like this have little ornamental value.
Geological facts
Quartzite is one of the most durable and resistant rocks found on Earth's surface. It is often tougher than its parent sandstone due to the interlocking nature of its recrystallized quartz grains.
Field identification & locations
Identify in the field by its inability to be scratched by steel, its grainy yet fused appearance, and its resistance to chemical weathering. Found worldwide in mountain ranges and riverbeds.
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