sedimentary
Jasper
Microcrystalline Quartz (SiO2)
Mohs hardness of 6.5 to 7, various colors including red, brown, yellow, and green due to iron oxide impurities, waxy to dull luster, cryptocrystalline structure, conchoidal fracture, specific gravity of 2.58 to 2.91.
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Physical properties
Mohs hardness of 6.5 to 7, various colors including red, brown, yellow, and green due to iron oxide impurities, waxy to dull luster, cryptocrystalline structure, conchoidal fracture, specific gravity of 2.58 to 2.91.
Formation & geological history
Formed through the precipitation of silica-rich fluids in sedimentary environments or hydrothermal veins, often associated with volcanic activity and ancient ocean basins, dating from Precambrian to modern times.
Uses & applications
Used for ornamental carvings, cabochons, jewelry, mosaic work, and as a popular specimen for rock collectors.
Geological facts
Jasper has been used since antiquity for seals, talismans, and jewelry, with mentions in ancient Mesopotamian and Egyptian texts. Its name comes from the ancient Greek word iaspis, meaning 'spotted stone'.
Field identification & locations
Can be identified in the field by its hardness (scratches glass), lack of cleavage, waxy luster, and opaque appearance. Commonly found in riverbeds, glacial drift, and areas of ancient volcanic or hydrothermal activity worldwide.
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