Rock Identifier
Polished jasper pebble (Jasper, microcrystalline quartz (SiO₂) with iron-oxide impurities) — mineral
mineral

Polished jasper pebble

Jasper, microcrystalline quartz (SiO₂) with iron-oxide impurities

AI-generated identification · may be incorrect

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.

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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.