metamorphic
River Stone (Quartzite)
Metamorphosed Sandstone (SiO2)
Hardness: 7 on Mohs scale; Color: yellowish-tan to olive-drab; Luster: matte to dull; Crystal structure: granular/non-foliated; Cleavage: none; Specific gravity: 2.6-2.7.
- Hardness
- 7 on Mohs scale
- Color
- yellowish-tan to olive-drab
- Luster
- matte to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: yellowish-tan to olive-drab; Luster: matte to dull; Crystal structure: granular/non-foliated; Cleavage: none; Specific gravity: 2.6-2.7.
Formation & geological history
Formed from quartz-rich sandstone subjected to high heat and pressure, causing recrystallization. The rounded shape is a result of fluvial erosion (water wear) in a river or coastal environment over thousands of years.
Uses & applications
Used in decorative landscaping, interior design as zen stones, construction aggregate, and occasionally for lapidary work (engraving).
Geological facts
Quartzite is one of the most physically tough and chemically resistant rocks found on the Earth's surface. This specimen's egg-like shape is a perfect example of saltation and abrasion in a riverbed.
Field identification & locations
Identified by its extreme hardness (cannot be scratched by a steel blade) and smooth, water-worn texture. Found globally in riverbeds, glacial deposits, and beaches. Focus on the grainy texture beneath the smooth surface.
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