metamorphic
Quartzite (River Stone)
SiO2 (Silicon Dioxide)
Hardness: 7 on Mohs scale; Color: White to light tan with reddish-brown iron staining; Luster: Vitreous to waxy; Texture: Granular, crystalline; Cleavage: None (conchoidal fracture)
- Hardness
- 7 on Mohs scale
- Color
- White to light tan with reddish-brown iron staining
- Luster
- Vitreous to waxy
Identified More metamorphic →
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Physical properties
Hardness: 7 on Mohs scale; Color: White to light tan with reddish-brown iron staining; Luster: Vitreous to waxy; Texture: Granular, crystalline; Cleavage: None (conchoidal fracture)
Formation & geological history
Formed from the metamorphism of quartz sandstone under high heat and pressure. This specific specimen is water-worn (tumbled), likely from a river or glacial deposit in the Missouri/Mississippi River basin region.
Uses & applications
Commonly used as construction aggregate, ballast, landscaping stone, and occasionally for lapidary work if highly translucent.
Geological facts
Quartzite is harder and more durable than the sandstone it originates from. The location (near St. Louis, MO) is rich in geological history involving ancient inland seas and significant glacial transport of rocks from the north.
Field identification & locations
Identify by its inability to be scratched by a steel knife and lack of reaction to acid. In the St. Louis area, these are frequently found in gravel bars and creek beds.
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