
mineral
Polished yellow-green chalcedony (likely serpentine or quartz pebble)
Microcrystalline quartz, SiO₂ (if chalcedony); possible antigorite/lizardite, Mg₃Si₂O₅(OH)₄ (if serpentine)
AI-generated identification · may be incorrectSmooth tumbled, waxy-to-glassy luster, pale yellow-green with orange-brown inclusions, no visible cleavage; estimated Mohs hardness 6.5–7 for chalcedony or 2.5–5.5 for serpentine. Rounded shape indicates polishing or water wear.
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Physical properties
Smooth tumbled, waxy-to-glassy luster, pale yellow-green with orange-brown inclusions, no visible cleavage; estimated Mohs hardness 6.5–7 for chalcedony or 2.5–5.5 for serpentine. Rounded shape indicates polishing or water wear.
Formation & geological history
Chalcedony forms when silica-rich groundwater fills cavities and fractures, commonly in volcanic rocks; serpentine forms by hydrothermal alteration of ultramafic rocks. Precise age and identification require hardness, streak, and specific-gravity testing.
Uses & applications
Used as a decorative tumbled stone, cabochon, bead, or carving material; chalcedony is more durable for jewelry, while serpentine is mainly ornamental. Common tumbled specimens generally have modest value.
Geological facts
The translucent, waxy appearance is consistent with chalcedony, but the unusually yellow-green body color can also indicate serpentine or iron-bearing quartz. Photography alone cannot reliably distinguish these materials.
Field identification & locations
Common sources include volcanic terrains for chalcedony and ultramafic belts such as California, New Zealand, Canada, and Italy for serpentine. A steel file or quartz scratch test helps: chalcedony scratches glass; softer serpentine usually does not.
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