metamorphic
Quartzite River Rock
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: Off-white, tan, or yellowish due to iron impurities; Luster: Vitreous to dull; Crystal structure: Trigonal (granular); Cleavage: None; Specific Gravity: 2.6-2.7.
- Hardness
- 7 on Mohs scale
- Color
- Off-white, tan, or yellowish due to iron impurities
- Luster
- Vitreous to dull
Identified More metamorphic →
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Physical properties
Hardness: 7 on Mohs scale; Color: Off-white, tan, or yellowish due to iron impurities; Luster: Vitreous to dull; Crystal structure: Trigonal (granular); Cleavage: None; Specific Gravity: 2.6-2.7.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, typically in orogenic belts. This specific specimen has been rounded by fluvial action (river transport).
Uses & applications
Used primarily in construction as crushed stone or gravel, and frequently as decorative landscaping stones due to its durability and color.
Geological facts
Quartzite is so tough that it often survives environmental weathering better than the surrounding rocks, which is why it is frequently found as rounded cobbles in riverbeds and glacial deposits.
Field identification & locations
Identify by its ability to scratch glass easily and its lack of reaction to acid. Look for a sugary, granular texture beneath the smooth, water-worn surface.
