mineral
Polished yellow jasper or iron-rich chert
Microcrystalline quartz (SiO₂) with iron-oxide inclusions
AI-generated identification · may be incorrectOpaque mustard-yellow to brown, waxy/glassy luster, irregular fracture, and likely Mohs hardness 6.5–7; the rounded surface appears naturally worn or polished. Exact identification is uncertain from a photograph alone.
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Physical properties
Opaque mustard-yellow to brown, waxy/glassy luster, irregular fracture, and likely Mohs hardness 6.5–7; the rounded surface appears naturally worn or polished. Exact identification is uncertain from a photograph alone.
Formation & geological history
Forms when silica-rich groundwater replaces or cements sediments, with goethite/hematite producing the yellow-brown coloration; commonly Cenozoic to Precambrian depending on locality.
Uses & applications
Used as ornamental stone, cabochons, beads, carvings, and inexpensive lapidary material; not generally used for construction.
Geological facts
The dark circular area may be an iron-oxide concentration, cavity, or surface inclusion rather than a crystal or fossil.
Field identification & locations
Jasper is opaque and does not show quartz crystal faces; a steel file should barely scratch it, while it can scratch ordinary glass. Common sources include Oregon, California, Utah, Brazil, India, and Australia.
