mineral
Yellow jasper or iron-stained chert
Microcrystalline quartz (SiO₂), commonly colored by goethite/limonite and other iron oxides
AI-generated identification · may be incorrectTypically Mohs hardness 6.5–7, opaque mustard-yellow to brown, with a waxy to dull luster and no visible cleavage; massive cryptocrystalline quartz, with conchoidal fracture. The rounded, wet surface obscures diagnostic texture, so exact identification is uncertain from the image alone.
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Physical properties
Typically Mohs hardness 6.5–7, opaque mustard-yellow to brown, with a waxy to dull luster and no visible cleavage; massive cryptocrystalline quartz, with conchoidal fracture. The rounded, wet surface obscures diagnostic texture, so exact identification is uncertain from the image alone.
Formation & geological history
Forms when silica-rich groundwater replaces or cements sediment, often incorporating iron oxides; it may occur in sedimentary or volcanic environments, with ages ranging from ancient Precambrian deposits to recent gravels.
Uses & applications
Used as ornamental stone, lapidary material, cabochons, carvings, tumbled stones, and sometimes aggregate; generally not a major industrial gemstone.
Geological facts
Yellow jasper is a variety name rather than a rigorously defined mineral species; color commonly comes from hydrated iron oxides. A glassy edge or conchoidal chip would support jasper/chert identification.
Field identification & locations
Common in river gravels and silica-rich outcrops worldwide, including the western United States, Brazil, India, Madagascar, and Australia. Test hardness against steel or glass, inspect a fresh fracture, and check for quartz-like translucency; avoid destructive testing if valuable.
