sedimentary
Jasper (with Manganese or Iron inclusions)
Silicon Dioxide (SiO2)
Hardness: 6.5–7 (Mohs scale); Color: Brownish-tan with dark speckles; Luster: Dull to waxy; Crystal Structure: Microcrystalline/Cryptocrystalline (trigonal); Cleavage: None; Specific Gravity: 2.58–2.91.
- Hardness
- 6
- Color
- Brownish-tan with dark speckles
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5–7 (Mohs scale); Color: Brownish-tan with dark speckles; Luster: Dull to waxy; Crystal Structure: Microcrystalline/Cryptocrystalline (trigonal); Cleavage: None; Specific Gravity: 2.58–2.91.
Formation & geological history
Formed through the infiltration of silica-rich fluids into volcanic ash or fine sedimentary layers. Over time, the silica crystallizes into microcrystalline quartz, trapping mineral impurities (like iron and manganese oxides) that create the speckled pattern. Often found in ancient hydrothermal deposits.
Uses & applications
Commonly used in the lapidary arts for making cabochons, beads, and tumbled stones. Historically used for making tools due to its conchoidal fracture, and currently popular as a 'healing crystal' or pocket stone.
Geological facts
Jasper is an opaque variety of chalcedony. The word 'jasper' is derived from the Greek word 'iaspis,' meaning spotted stone. It has been a favored gemstone for thousands of years, appearing in the artifacts of the Minoan civilization on Crete.
Field identification & locations
Identify by its opacity (does not let light through), waxy texture when polished, and high hardness (it will scratch glass). Commonly found in riverbeds, deserts, and volcanic regions globally, notably in the USA (Oregon, Idaho), Brazil, and India.
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