mineral
Yellow jasper (likely iron-stained chalcedony)
Microcrystalline quartz, SiO₂, commonly colored by iron oxides/hydroxides
AI-generated identification · may be incorrectOpaque mustard-yellow, earthy to waxy luster, fine-grained and possibly tumbled or naturally rounded; quartz hardness is about 6.5–7 Mohs, with no visible cleavage and conchoidal fracture. Exact identification requires testing because the image cannot distinguish jasper from yellow chert or iron-rich stone.
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Physical properties
Opaque mustard-yellow, earthy to waxy luster, fine-grained and possibly tumbled or naturally rounded; quartz hardness is about 6.5–7 Mohs, with no visible cleavage and conchoidal fracture. Exact identification requires testing because the image cannot distinguish jasper from yellow chert or iron-rich stone.
Formation & geological history
Forms when silica-rich groundwater fills cavities or replaces sediments, while iron compounds create the yellow coloration; deposits range from ancient to geologically recent. Common in volcanic terrains, sedimentary chert beds, and weathered iron-rich zones.
Uses & applications
Used as a lapidary material for cabochons, carvings, beads, and polished specimens; not generally used as a construction aggregate. Common pieces are mainly of modest collecting value.
Geological facts
Jasper is an opaque variety of microcrystalline quartz, unlike translucent chalcedony. Yellow color typically reflects limonite or goethite staining rather than a distinct quartz variety.
Field identification & locations
Look for consistent fine texture, glassy/conchoidal fracture, lack of cleavage, and inability to scratch it with a steel knife; it should scratch window glass. Common worldwide, including India, Madagascar, Brazil, Australia, and the western United States.
