metamorphic
Quartzite with Iron Staining
Silicon Dioxide (SiO2) with Fe2O3 impurities
Hardness: 7 (Mohs scale), Color: White to creamy with yellowish-orange iron staining, Luster: Vitreous to greasy, Crystal structure: Trigonal (granular texture), Cleavage: None (conchoidal fracture)
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Physical properties
Hardness: 7 (Mohs scale), Color: White to creamy with yellowish-orange iron staining, Luster: Vitreous to greasy, Crystal structure: Trigonal (granular texture), Cleavage: None (conchoidal fracture)
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone. High heat and pressure cause the sand grains to recrystallize and fuse together, typically in orogenic belts. This specific piece shows significant water-rolling and oxidation (iron staining) from surface exposure.
Uses & applications
Used in construction as crushed stone, in glass manufacturing if highly pure, as a refractory material, and as a decorative stone in landscaping or river rock collections.
Geological facts
Quartzite is so tough that it often outlasts the mountain ranges it forms in, remaining as resistant ridges or rounded river cobbles long after softer rocks have eroded away.
Field identification & locations
Identify in the field by its extreme hardness (it will easily scratch glass and stainless steel) and its granular, sugary appearance on a fresh break. It lacks the layered cleavage of calcite and the visible grains of sandstone.
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