sedimentary
Polished orbicular jasper pendant
Orbicular jasper (microcrystalline quartz/chalcedony, SiO₂)
AI-generated identification · may be incorrectDark green-black polished stone with pale rounded orbicules; opaque, vitreous to waxy luster, cryptocrystalline structure, no visible cleavage, and Mohs hardness about 6.5–7. Specific gravity is typically 2.55–2.70.
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Physical properties
Dark green-black polished stone with pale rounded orbicules; opaque, vitreous to waxy luster, cryptocrystalline structure, no visible cleavage, and Mohs hardness about 6.5–7. Specific gravity is typically 2.55–2.70.
Formation & geological history
Orbicular jasper forms when silica-rich volcanic or hydrothermal material develops concentric mineral-growth patterns around nuclei, later silicified; the exact geological age depends on locality. The specimen is shaped and polished, likely for jewelry.
Uses & applications
Used primarily for cabochons, pendants, beads, and ornamental objects; it has modest collector value when orbicules are distinct and attractive.
Geological facts
Orbicular patterns may include quartz/chalcedony with chlorite, epidote, feldspar, or iron oxides, producing green, cream, red, or black colors.
Field identification & locations
Identify it by its opaque fine-grained body, rounded contrasting orbs, and ability to scratch glass; it lacks the translucent crystalline appearance of agate. Common sources include Madagascar, Mexico, Australia, and Indonesia; exact origin cannot be determined visually.