sedimentary
Yellow Jasper
Silicon Dioxide (SiO2 with iron oxide inclusions)
Hardness of 6.5-7 on the Mohs scale, opaque mustard to brownish-yellow color, waxy to dull luster, microcrystalline/cryptocrystalline trigonal structure, smooth conchoidal fracture with no cleavage.
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Physical properties
Hardness of 6.5-7 on the Mohs scale, opaque mustard to brownish-yellow color, waxy to dull luster, microcrystalline/cryptocrystalline trigonal structure, smooth conchoidal fracture with no cleavage.
Formation & geological history
Formed when fine microcrystalline quartz precipitates from silica-rich waters, incorporating iron oxide minerals (goethite or hematite) that impart the characteristic yellow color. Found in sedimentary environments and alluvial deposits.
Uses & applications
Popular for lapidary work, cabochons, tumbled decorative stones, jewelry, carving, and rock collections.
Geological facts
Jasper has been used since antiquity for seals, ornaments, and amulets. Yellow jasper specifically gets its vibrant color from hydrated iron oxides trapped inside the quartz matrix.
Field identification & locations
Can be identified in the field by its distinct mustard-yellow opaque hue, smooth conchoidal fracturing, and high hardness (scratches glass easily). Common in regions with ancient sedimentary rocks and riverbeds across Brazil, South Africa, Madagascar, and the Western United States.
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