Figure F26. Photomicrograph showing a network of talc veins replacing serpentine and crosscutting chrysotile veins. Talc veins also replace the centers of serrate serpentine veins. This image demonstrates that talc alteration was initiated after serpentinization had reached an advanced stage, indicated by the presence of transitional to nonpseudomorphic textures of serpentine. Furthermore, the talc veins are crosscutting wispy chrysotile veins, which in turn crosscut even earlier chrysotile + magnetite veins. These relationships indicate that talc alteration occurred at a late stage during the metamorphic evolution of the rock (Sample 209-1268A-15R-3, 135–137 cm) (cross-polarized light: blue + gray filters; field of view = 1.4 mm; image 1268A_055).