mineral
Tumbled yellow jasper
Jasper, microcrystalline quartz (SiO₂) colored by iron oxides
AI-generated identification · may be incorrectOpaque mustard-yellow, fine-grained, matte to waxy luster; hardness about 6.5–7 Mohs, no visible cleavage, conchoidal fracture, and typical quartz density near 2.6 g/cm³. The rounded shape indicates tumbling or natural water wear.
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Physical properties
Opaque mustard-yellow, fine-grained, matte to waxy luster; hardness about 6.5–7 Mohs, no visible cleavage, conchoidal fracture, and typical quartz density near 2.6 g/cm³. The rounded shape indicates tumbling or natural water wear.
Formation & geological history
Forms when silica-rich fluids replace or cement sediment, incorporating iron oxides that create the yellow-brown color; specimens may range from Precambrian to much younger. Common sources include Brazil, India, Madagascar, Indonesia, and the western United States.
Uses & applications
Used for cabochons, beads, carvings, lapidary decoration, and inexpensive polished stones; rarely used as a minor ornamental aggregate.
Geological facts
Jasper is an opaque variety of chalcedony or microcrystalline quartz, unlike transparent crystalline quartz. Color zoning and iron staining are common.
Field identification & locations
Identify by its opaque, uniformly fine texture, lack of cleavage, waxy surface, and resistance to scratching by steel; a glass scratch test is more diagnostic but may damage it. Exact locality cannot be determined reliably from the photograph.
