mineral
Tumbled agate
Microcrystalline quartz (SiO₂), likely agate or chalcedony
AI-generated identification · may be incorrectPolished, opaque-to-translucent tan and cream stone with mottled brown areas and a waxy-to-glassy luster. Quartz hardness is 6.5–7; crystals are trigonal, but the material is microcrystalline and has no visible cleavage.
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Physical properties
Polished, opaque-to-translucent tan and cream stone with mottled brown areas and a waxy-to-glassy luster. Quartz hardness is 6.5–7; crystals are trigonal, but the material is microcrystalline and has no visible cleavage.
Formation & geological history
Forms as silica-rich fluids deposit concentric or irregular layers in cavities, commonly in volcanic rocks. The image alone does not establish the specimen’s precise variety, source, or age.
Uses & applications
Used for tumbling, jewelry, ornaments, and small decorative objects; agate is also used for precision components and carvings.
Geological facts
Agate is a banded variety of chalcedony, though some specimens have subtle or indistinct banding.
Field identification & locations
The rounded shape and polished surface indicate tumbling; hardness and fine silica texture are consistent with chalcedony. Agates occur worldwide, including Brazil, Uruguay, India, and the western United States.
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Mineral