metamorphic
Quartzite with Feldspar
Quartzite (mainly SiO2) with inclusions of Potassium Feldspar (KAlSi3O8)
Hardness: 7 (Mohs scale), Color: White to light grey with pink/peach staining/inclusions, Luster: Vitreous to greasy, 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: White to light grey with pink/peach staining/inclusions, Luster: Vitreous to greasy, 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, quartz grains recrystallize and fuse together. The pinkish hues suggest presence of iron oxides or feldspar impurities.
Uses & applications
Used primarily in construction as crushed stone for road gravel or railroad ballast; also used as a decorative stone in landscaping or as masonry veneers.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rock in weathering processes, frequently found as rounded cobbles in riverbeds long after the parent mountain has eroded away.
Field identification & locations
Identify by its ability to scratch glass and its grainy, sugary texture under a lens. It will not fizz with acid (unlike marble). Commonly found in mountain belts and glacial deposits.
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