Figure F10. Contact between jasperoid and altered wallrock fragment in Sample 193-1189B-6R-1 (Piece 2, 13–15 cm) showing a veinlike extension of the jasperoid cutting the wallrock and separating a phenocryst of unaltered plagioclase. Immediately adjacent to the vein, the clay-rich wallrock has been silicified by poikiloblastic quartz patches with epitaxial orientations relative to vein quartz grains. Some wallrock fragments have been replaced by scattered prismatic quartz crystals with similar poikiloblastic outgrowths. There is no selvage of inclusion-free quartz at wallrock contacts in this sample, unlike nearby Piece 5 (see Fig. F8, p. 17). Width of view = 1.4 mm; ordinary light.

Figure F10. Contact between jasperoid and altered wallrock fragment in Sample 193-1189B-6R-1 (Piece 2, 13–15 cm) showing a veinlike extension of the jasperoid cutting the wallrock and separating a phenocryst of unaltered plagioclase. Immediately adjacent to the vein, the clay-rich wallrock has been silicified by poikiloblastic quartz patches with epitaxial orientations relative to vein quartz grains. Some wallrock fragments have been replaced by scattered prismatic quartz crystals with similar poikiloblastic outgrowths. There is no selvage of inclusion-free quartz at wallrock contacts in this sample, unlike nearby Piece 5 (see Fig. F8). Width of view = 1.4 mm; ordinary light.