Post #1869289

This agate displays beautiful fortification banding with warm earth tones created by varying iron oxide concentrations during formation. The tight, concentric bands formed as silica-rich solutions deposited successive layers in a volcanic vesicle. Notice how the banding follows the cavity walls, indicating slow, rhythmic precipitation over time. The color gradation from cream to deep brown reflects different oxidation states of iron impurities in the microcrystalline quartz structure…