metamorphic
Yellow Quartzite (River Stone)
Quartzite (composed primarily of Quartz: SiO2)
Hardness: 7 (Mohs scale), Color: honey-yellow to tan, Luster: Vitreous/Waxy (dull when weathered), Crystal Structure: Trigonal (microcrystalline), Cleavage: None/Conchoidal fracture, Specific Gravity: 2.6-2.65
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Physical properties
Hardness: 7 (Mohs scale), Color: honey-yellow to tan, Luster: Vitreous/Waxy (dull when weathered), Crystal Structure: Trigonal (microcrystalline), Cleavage: None/Conchoidal fracture, Specific Gravity: 2.6-2.65
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure. This specific specimen has been further shaped by fluvial (river) erosion, giving it a rounded, tumbled appearance.
Uses & applications
Used primarily in landscaping, garden decoration, and as architectural aggregate. Higher quality pieces may be used for lapidary work or as worry stones.
Geological facts
Quartzite is one of the most durable rocks on Earth's surface. It can be harder than steel and is highly resistant to chemical weathering, which is why it often survives as smooth pebbles in riverbeds.
Field identification & locations
Identify in the field by its hardness (it will scratch glass) and its sugary, crystalline texture seen under a lens. Found globally in riverbeds, beaches, and glaciated regions. Look for smooth, rounded shapes with a matte finish that brightens when wet.
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