Plate P5. Photomicrographs of vein minerals in Hole 735B. 1. A felsic patch in gabbro in which amphibole is replacing plagioclase (irregular, light gray patch on right side). The amphibole is strongly zoned from dark brown to light brown and from dark gre

Plate P5. 3. A different part of the same vein as in 2. Here the natrolite forms small white crystals with square cross-sections in a matrix of light brown aphanitic material. Carbonate fills the irregular parallel crack just above the zeolite vein (Sample 176-735B-181R-1, 131-136 cm). All scale bars = 1 mm.