Figure F17. Photomicrograph from the edge of a black patch in Unit 15. Note that the scale differs from Figures F15, , and F16, . The image shows the millimeter-wide finer grained rim zone of the patch with relict bladed crystals (now clear grains with lineations of opaque grains) and interstitial variolitic skeletal plagioclases. The host rock (top) contains microlites oriented parallel to the contact (Sample 193-1189A-8R-1 [Piece 17, 103-105 cm]; width of view = 1.38 mm. Photomicrograph ID# 1189A

Figure F17. Photomicrograph from the edge of a black patch in Unit 15. Note that the scale differs from Figures F15 and F16. The image shows the millimeter-wide finer grained rim zone of the patch with relict bladed crystals (now clear grains with lineations of opaque grains) and interstitial variolitic skeletal plagioclases. The host rock (top) contains microlites oriented parallel to the contact (Sample 193-1189A-8R-1 [Piece 17, 103-105 cm]; width of view = 1.38 mm. Photomicrograph ID# 1189A_98; thin section 54).