mineral
Polished jasper or iron-stained chert
Microcrystalline quartz (SiO₂), commonly chalcedony with iron-oxide staining
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; orange-brown, cream, and gray coloration; waxy to subvitreous luster; cryptocrystalline structure with no visible cleavage and conchoidal fracture. The rounded shape appears tumbled or naturally water-worn.
Identified More mineral →
Explore Polished jasper or iron-stained chert in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness about 6.5–7 Mohs; orange-brown, cream, and gray coloration; waxy to subvitreous luster; cryptocrystalline structure with no visible cleavage and conchoidal fracture. The rounded shape appears tumbled or naturally water-worn.
Formation & geological history
Forms when silica-rich groundwater replaces or fills cavities in volcanic or sedimentary rocks, with hematite/goethite producing the orange-brown colors. Formation age varies widely by locality, commonly Paleozoic to Cenozoic.
Uses & applications
Used for cabochons, carvings, beads, ornaments, and lapidary specimens; attractive pieces have modest collectible value.
Geological facts
Jasper is an opaque variety of chalcedony, while chert is a closely related microcrystalline quartz rock. Iron staining can create vivid brecciated, orbicular, or landscape-like patterns.
Field identification & locations
Identify by its glass-scratching hardness, opaque appearance, waxy luster, and lack of cleavage; acid produces no fizz. Common in volcanic terrains, river gravels, and silica-rich sedimentary formations worldwide.
