mineral

Tumbled yellow jasper

Jasper, microcrystalline quartz (SiO₂) colored mainly by iron oxides

AI-generated identification · may be incorrect

Opaque mustard-yellow to golden-brown, with mottled cream and rusty areas; waxy to dull luster and no visible crystals. Hardness is about 6.5–7 Mohs, specific gravity roughly 2.5–2.7, and fracture is typically conchoidal to uneven; cleavage absent.

Identified August 19, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater replaces or fills cavities in volcanic rocks, incorporating iron-bearing impurities; specimens may be Paleozoic to Cenozoic depending on locality. The rounded shape indicates human tumbling and polishing.

Uses & applications

Used for cabochons, beads, carvings, ornamental objects, and inexpensive jewelry; attractive patterned pieces are popular lapidary material.

Geological facts

Jasper is a variety of chalcedony or microcrystalline quartz, though the term is often used broadly for opaque silica-rich rocks. Yellow coloration commonly reflects hydrated iron oxides such as limonite or goethite.

Field identification & locations

Identify it by its opacity, fine-grained texture, yellow iron staining, lack of cleavage, and ability to scratch ordinary glass; it should not show large crystal faces. Common sources include Madagascar, India, Brazil, Australia, and the western United States.