mineral

Polished agate or chalcedony slice (uncertain)

Microcrystalline quartz, SiO₂; possibly fossil-bearing chalcedony

AI-generated identification · may be incorrect

Pale blue-green, translucent, waxy to vitreous luster, with irregular pale banding or internal cavities. Quartz hardness is about 7 Mohs; no obvious cleavage, conchoidal fracture, and specific gravity near 2.6.

Identified August 17, 2026More mineral →

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Physical properties

Formation & geological history

Agate forms when silica-rich groundwater fills cavities in volcanic rock, depositing chalcedony in layers over time; associated host rocks are commonly Paleozoic to Cenozoic. The visible central structure could alternatively be a silicified fossil or coral fragment.

Uses & applications

Used for cabochons, jewelry, carvings, lapidary pieces, and decorative objects; lower-grade material is used as ornamental stone.

Geological facts

Agate’s banding reflects repeated changes in fluid chemistry and silica deposition. Blue-green coloration may be natural or enhanced by dye, lighting, or surface treatment.

Field identification & locations

Look for curved chalcedony banding, translucency, waxy luster, and hardness sufficient to scratch glass; a loupe can reveal fibrous quartz texture. Common sources include Brazil, Uruguay, Mexico, India, Madagascar, and the United States.