Figure 21. Photomicrograph of the intersection of calcite veins with palagonite. Silica, Fe oxyhydroxides, and Mn oxide line the edges of the calcite vein. Palagonite is altered to clay along dendritic alteration front. The vertical fracture within the palagonite contains Mn/Fe oxyhydroxides and silica (Sample 187-1155B-2R-1, 68-71 cm).