sedimentary
Jasper with Iron Staining
Silicon Dioxide (SiO2) with Hematite impurities
Hardness: 6.5-7 (Mohs scale); Color: Red-brown, grey, tan with black staining; Luster: Dull to waxy; Structure: Microcrystalline quartz; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91
- Hardness
- 6
- Color
- Red-brown, grey, tan with black staining
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Red-brown, grey, tan with black staining; Luster: Dull to waxy; Structure: Microcrystalline quartz; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91
Formation & geological history
Formed through the infiltration of silica-rich fluids into volcanic ash or fine sediment, often enriched with iron oxides. This specific sample shows significant water-rounding and chemical weathering, suggesting an alluvial or stream-bed history.
Uses & applications
Used primarily for lapidary work, jewelry (cabochons), river rock landscaping, and as a collector's specimen for hobbyists.
Geological facts
Jasper has been used as a gemstone for thousands of years; it was mentioned in many ancient texts and used in the breastplates of high priests. The reddish hue typically comes from Fe2O3 (hematite).
Field identification & locations
Identify in the field by its hardness (will scratch glass), smooth water-worn surface, and lack of visible grains. Common in riverbeds and glacial tills. This piece shows a distinct dark patina, possibly manganese or iron oxide 'desert varnish'.
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