mineral
Tumbled pale agate or chalcedony
Microcrystalline quartz (SiO₂), likely banded chalcedony/agate
AI-generated identification · may be incorrectSmall polished, translucent cream-to-pink specimen with orange-brown internal bands or inclusions and a waxy-to-glassy luster. Quartz hardness is about 7 Mohs; it has a cryptocrystalline structure, no visible cleavage, and specific gravity near 2.6.
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Physical properties
Small polished, translucent cream-to-pink specimen with orange-brown internal bands or inclusions and a waxy-to-glassy luster. Quartz hardness is about 7 Mohs; it has a cryptocrystalline structure, no visible cleavage, and specific gravity near 2.6.
Formation & geological history
Forms when silica-rich groundwater fills cavities in volcanic rock, depositing successive layers of chalcedony and quartz. The exact age cannot be determined visually; agates occur in volcanic rocks from many geologic periods.
Uses & applications
Used for cabochons, beads, ornaments, paperweights, and educational collections; this small piece has modest commercial value.
Geological facts
Agate’s curved or concentric banding reflects changing chemistry during cavity filling. The orange coloration commonly comes from iron oxides or hydroxides.
Field identification & locations
Identify it by its translucency, waxy polish, hardness, and fine curved banding; it should resist scratching by a steel knife but be scratched by quartz. Common sources include Brazil, Uruguay, India, Madagascar, and the western United States.
