sedimentary
Jasper
Microcrystalline Quartz (SiO2)
Hardness of 6.5 to 7 on the Mohs scale, typically brown, red, yellow, or green due to iron and other mineral impurities, vitreous to dull luster, cryptocrystalline crystal structure, conchoidal fracture with no true cleavage, and a specific gravity of 2.58 to 2.91.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, typically brown, red, yellow, or green due to iron and other mineral impurities, vitreous to dull luster, cryptocrystalline crystal structure, conchoidal fracture with no true cleavage, and a specific gravity of 2.58 to 2.91.
Formation & geological history
Forms from silica-rich solutions precipitating in sedimentary environments or filling cavities in volcanic rocks, often through the alteration of silicified sediments or hydrothermal processes.
Uses & applications
Widely used in ornamental carvings, cabochons, jewelry, decorative objects, and as a popular specimen for rock collectors.
Geological facts
Jasper has been used since ancient times to create seals, signet rings, and intricate ornamental weapons or jewelry. Its name derives from the ancient Greek word iaspis, meaning 'spotted or speckled stone'.
Field identification & locations
Identified in the field by its opaque appearance, waxy to dull luster, conchoidal fracture, and rich earthy color patterns. It is found worldwide, with major deposits in India, Russia, Brazil, Egypt, and the USA.
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