mineral
Polished jasper pebble
Jasper, microcrystalline quartz (SiO₂) with iron-oxide impurities
AI-generated identification · may be incorrectOpaque reddish-brown, mustard-yellow and olive-green coloration; waxy to glassy luster when polished; hardness about 6.5–7 Mohs; cryptocrystalline quartz, with no visible cleavage and irregular/conchoidal fracture. The rounded shape indicates tumbling or water wear.
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Physical properties
Opaque reddish-brown, mustard-yellow and olive-green coloration; waxy to glassy luster when polished; hardness about 6.5–7 Mohs; cryptocrystalline quartz, with no visible cleavage and irregular/conchoidal fracture. The rounded shape indicates tumbling or water wear.
Formation & geological history
Jasper forms when silica-rich fluids replace or cement volcanic ash, sediments, or other rocks, with iron and other minerals producing the colors; ages range from Precambrian to recent. Common sources include Brazil, India, Madagascar, Australia, Mexico, and the western United States.
Uses & applications
Used for cabochons, beads, carvings, ornaments, and lapidary specimens; occasionally used as decorative stone. This small polished piece is primarily a collector or craft item.
Geological facts
Jasper is technically a variety of opaque chalcedony or microcrystalline quartz, not a single mineral species. The green tones may reflect chlorite or other iron-bearing inclusions, while red-brown tones commonly come from hematite or goethite.
Field identification & locations
Identify it by its opacity, fine-grained texture, strong color patterns, and resistance to scratching; it should not show individual quartz crystals. A streak test on unglazed ceramic is usually white to pale brown, and a steel blade generally does not scratch it.
