metamorphic
Quartzite with Iron Inclusions
Metamorphic Quartzite (SiO2 with Fe2O3 trace impurities)
Hardness: 7 (Mohs scale), Color: tan to creamy white with orange/amber staining, Luster: Vitreous to waxy, Crystal Structure: Hexagonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.6 - 2.8
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Physical properties
Hardness: 7 (Mohs scale), Color: tan to creamy white with orange/amber staining, Luster: Vitreous to waxy, Crystal Structure: Hexagonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.6 - 2.8
Formation & geological history
Formed through the regional metamorphism of quartz sandstone. Under intense heat and pressure, quartz grains recrystallize into an interlocking mosaic. The orange tint is caused by the oxidation of iron minerals within the rock, often occurring over millions of years.
Uses & applications
Used primarily in construction (crushed stone), as architectural stone, and occasionally for lapidary work or aquarium decor. High-purity quartzite is used to produce silica sand for glassmaking.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rock, forming resistant ridges and hilltops. It is one of the hardest commonly found rocks and will easily scratch glass or steel.
Field identification & locations
Identify in the field by its sugary, granular texture and its inability to be scratched by a steel nail. This specimen is a river-tumbled 'cobble' or 'pebble' frequently found in glacial till or stream beds across North America and Europe.
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