metamorphic
Quartzite Pebble (with Iron Staining)
Quartzite (SiO2)
Hardness: 7 (Mohs scale), Color: Pinkish-orange with tan/white patches due to iron oxide staining, Luster: Vitreous to waxy, Crystal Structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.6 – 2.7
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Physical properties
Hardness: 7 (Mohs scale), Color: Pinkish-orange with tan/white patches due to iron oxide staining, Luster: Vitreous to waxy, Crystal Structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.6 – 2.7
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure. This specimen has been significantly water-worn into a smooth pebble, likely through fluvial (river) or coastal wave action over thousands of years.
Uses & applications
Common quartzite is used in construction as crushed stone or ballast. Rounded pebbles are popular for decorative landscaping, Zen gardens, and as tumbling media for hobbyist lapidary work.
Geological facts
Quartzite is so hard and chemically resistant that it often survives as pebbles long after the surrounding softer rocks have eroded away. The pink/orange coloring in this specific piece is typically caused by minute traces of hematite or limonite (iron oxides).
Field identification & locations
Identify in the field by its hardness (it will easily scratch glass) and its sugary, crystalline texture when broken. It differs from sandstone in that it breaks across the quartz grains rather than around them. Found globally in ancient mountain belts and riverbeds.
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