mineral
Polished/tumbled green jasper (probable serpentinized stone)
Jasper, microcrystalline quartz (SiO₂), possibly mixed with serpentine minerals
AI-generated identification · may be incorrectOpaque blue-green to olive-green with brown iron-oxide staining and a waxy-to-dull polish; typically Mohs 6.5–7 for jasper, though serpentine-rich material may be softer (2.5–5.5). Microcrystalline, with no visible cleavage and irregular fracture; specific gravity commonly about 2.5–2.8.
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Physical properties
Opaque blue-green to olive-green with brown iron-oxide staining and a waxy-to-dull polish; typically Mohs 6.5–7 for jasper, though serpentine-rich material may be softer (2.5–5.5). Microcrystalline, with no visible cleavage and irregular fracture; specific gravity commonly about 2.5–2.8.
Formation & geological history
Jasper forms when silica-rich fluids replace or cement volcanic sediment and breccia; green coloration may reflect chlorite, epidote, or serpentine, while brown areas are iron oxides. Such material is generally Precambrian to Cenozoic, depending on locality.
Uses & applications
Used for cabochons, beads, carvings, tumbled stones, and ornamental objects; attractive examples are popular with collectors but usually have modest value.
Geological facts
The specimen’s mottled green-brown pattern and smooth rounded shape indicate human tumbling or polishing. Exact identification requires hardness, streak, and perhaps thin-section or chemical testing.
Field identification & locations
Common in volcanic and hydrothermal terrains, including Oregon, California, Arizona, Australia, and South Africa. Test cautiously with a steel blade and quartz: true jasper resists scratching and leaves a white streak.
