Sedimentary / Metamorphic
Jasper and Quartz River Cobble
Silicon Dioxide (SiO2) with Hematite inclusions
Hardness: 6.5-7 on Mohs scale; Color: Rusty red (jasper) with grey/white patches (quartz); Luster: Dull to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture).
- Hardness
- 6
- Color
- Rusty red (jasper) with grey/white patches (quartz)
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Rusty red (jasper) with grey/white patches (quartz); Luster: Dull to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture).
Formation & geological history
Formed from silica-rich fluids precipitating in volcanic or sedimentary environments. The rounded shape indicates significant fluvial erosion (transportation by water) over thousands of years.
Uses & applications
Used primarily for lapidary work, tumbling, decorative landscaping, and as a collector's specimen for hobbyists.
Geological facts
Jasper is a variety of chalcedony that owes its red color to iron oxides (hematite). This specimen is a 'river rock,' meaning its smooth surface was naturally polished by abrasive contact with other rocks in a riverbed.
Field identification & locations
Identify in the field by its weight (dense), hardness (will scratch glass), and rounded smooth texture. Commonly found in riverbeds, glacial tills, and alluvial deposits worldwide.
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