metamorphic
Quartzite River Rock
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Tan, beige, or white; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.63-2.65
- Hardness
- 7 on Mohs scale
- Color
- Tan, beige, or white
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Tan, beige, or white; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.63-2.65
Formation & geological history
Formed through the metamorphism of quartz sandstone under high heat and pressure, typically during mountain-building events. This specific specimen has been further shaped and smoothed by fluvial (river) erosion over many years.
Uses & applications
Used primarily in construction as aggregate for roads, railroad ballast, and concrete. In landscaping, it is used for decorative river rock beds.
Geological facts
Quartzite is so durable that it often outlasts the mountain ranges from which it was once part. It is harder than steel and will easily scratch glass.
Field identification & locations
Identify in the field by its extreme hardness, lack of reaction to acid, and smooth, rounded water-worn texture. Commonly found in riverbeds, glacial deposits, and mountain outcroppings globally.
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