2.8" Polished Banded Bahia Agate Nodule Pair - Brazil

About Bahia Agates

Bahia agates come from the mineral-rich state of Bahia in eastern Brazil, a region famous for producing some of the world’s most beautifully patterned cryptocrystalline quartz. Formed in ancient volcanic host rock, agate begins its life as silica-rich fluids circulating through gas cavities and fractures left behind as lava cooled. Over long stretches of time, microscopic layers of chalcedony line those voids like the rings of a tree, gradually building inward. The vivid banding, fortification patterns, and eye formations seen in Bahia agate are the result of subtle shifts in temperature, pressure, and mineral content in those fluids—each pulse leaving behind a new micro-layer, often only fractions of a millimeter thick.

What sets Bahia material apart is its bold contrast and exceptional pattern diversity. Many specimens display classic parallel banding in earth tones, while others form dramatic “fortification” lines resembling aerial views of stone citadels, swirling moss-like dendrites, concentric “eyes,” or rare tube and sagenite inclusions that record the flow paths of the silica itself. Iron oxides contribute reds, oranges, and browns, while manganese and other trace elements can introduce smoky grays, pinks, or deeper dendritic details. Some rough nodules from the region also form alongside geode pockets lined with crystalline quartz, creating pieces that blend banded agate exteriors with sparkling druzy interiors.