mineral
Banded Agate (Chert / Chalcedony)
Silicon Dioxide (SiO2)
Hardness of 6.5-7 on Mohs scale, waxy to vitreous luster, microcrystalline structure, conchoidal fracture, yellowish-orange core with dark grey/greenish outer bands
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Physical properties
Hardness of 6.5-7 on Mohs scale, waxy to vitreous luster, microcrystalline structure, conchoidal fracture, yellowish-orange core with dark grey/greenish outer bands
Formation & geological history
Formed through the deposition of silica-rich fluids into cavities within volcanic or sedimentary rocks, creating concentric color layers over time.
Uses & applications
Polished into a pendant for jewelry; also widely used for lapidary carving, cabochons, and ornamental decorative stones.
Geological facts
Agate is a variety of chalcedony characterized by its fine grain and brightness of color. Concentric banding occurs due to rhythmic precipitation of iron and other trace minerals.
Field identification & locations
Identified by its distinctive concentric color banding and smooth texture when cut/polished. Commonly found in Brazil, Uruguay, Madagascar, India, and the United States.
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