metamorphic
Riverstone Quartzite
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: Grayish-brown to tan (due to iron staining); Luster: Dull/waxy when weathered; Crystal Structure: Granular/Microcrystalline; Cleavage: None (conchoïdal fracture); Specific Gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Grayish-brown to tan (due to iron staining)
- Luster
- Dull/waxy when weathered
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Physical properties
Hardness: 7 on Mohs scale; Color: Grayish-brown to tan (due to iron staining); Luster: Dull/waxy when weathered; Crystal Structure: Granular/Microcrystalline; Cleavage: None (conchoïdal fracture); Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure. This specimen has been further shaped by fluvial (river) erosion, which created its rounded, smooth cobble shape over thousands of years.
Uses & applications
Used primarily as decorative landscaping stone, drainage aggregate, or as a source of high-purity silica in industrial glassmaking and metallurgy.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rock layers during erosion. If you hit this stone with a hammer, it will typically break across the quartz grains rather than around them, distinguishing it from sandstone.
Field identification & locations
Identify in the field by its superior hardness (it will easily scratch glass or steel) and its smooth, water-worn texture often found in riverbeds or glacial tills. Collectors should look for internal translucency by shining a light through edges.
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