sedimentary (physico-chemical precipitate)
Jasper with Hematite (Red Jasper)
Silicon Dioxide with Iron Oxide (SiO2 and Fe2O3)
Hardness: 6.5–7 on Mohs scale. Color: Opaque red and dark gray to black. Luster: Dull to vitreous or waxy when polished. Crystal Structure: Hexagonal (microcrystalline). Cleavage: None (conchoidal fracture). Specific Gravity: 2.58–2.91.
- Hardness
- 6
- Color
- Opaque red and dark gray to black
- Luster
- Dull to vitreous or waxy when polished
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Physical properties
Hardness: 6.5–7 on Mohs scale. Color: Opaque red and dark gray to black. Luster: Dull to vitreous or waxy when polished. Crystal Structure: Hexagonal (microcrystalline). Cleavage: None (conchoidal fracture). Specific Gravity: 2.58–2.91.
Formation & geological history
Formed through the accumulation and silicification of microcrystalline quartz in hydrothermal veins or as a secondary mineral in volcanic deposits. The red color is caused by iron inclusions (hematite), often dating back to the Precambrian era.
Uses & applications
Used primarily in lapidary arts for cabochons, beads, and decorative carvings. It is popular in jewelry and as a pocket stone for collectors.
Geological facts
Jasper has been used throughout history as a 'nurturing stone' by many cultures. Some varieties with high hematite content are magnetic or have a significantly higher density than standard chalcedony.
Field identification & locations
Identify by its opaque nature (unlike translucent carnelian), its high hardness (won't be scratched by a steel knife), and its characteristic smooth, waxy feel when tumbled. Common in the western USA, Brazil, and South Africa.
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Banded Calcite (Mexican Onyx)
Calcium Carbonate (CaCO3)
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Hematite
Iron(III) oxide (Fe2O3)
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