sedimentary
Jasper (specifically Yellow/Red Jasper)
Silicon Dioxide (SiO2) with iron oxide inclusions
Hardness: 6.5-7 on Mohs scale. Color: Mustard yellow and brick red patterns. Luster: Dull to waxy when unpolished. Structure: Microcrystalline quartz (Trigonal). Cleavage: None (conchoidal fracture).
- Hardness
- 6
- Color
- Mustard yellow and brick red patterns
- Luster
- Dull to waxy when unpolished
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Physical properties
Hardness: 6.5-7 on Mohs scale. Color: Mustard yellow and brick red patterns. Luster: Dull to waxy when unpolished. Structure: Microcrystalline quartz (Trigonal). Cleavage: None (conchoidal fracture).
Formation & geological history
Formed as a result of mineral-rich water precipitating silica in the cracks of volcanic or sedimentary rocks. It often forms through the lithification of silica-rich sediments or volcanic ash during any geological era (Archean to Cenozoic).
Uses & applications
Commonly used for lapidary work, cabochons for jewelry, decorative carvings, and as a popular specimen for mineral collectors and 'rockhounds'.
Geological facts
Jasper is an opaque variety of quartz. Its name is derived from the Greek 'iaspis', meaning 'spotted stone.' Many believe it to be a stone of grounding and stability due to its earthy colors.
Field identification & locations
Identify in the field by its opacity (does not let light through even at edges), high hardness (will scratch glass), and characteristically smooth, river-worn or weathered exterior. Commonly found in riverbeds and gravel pits globally.
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