Figure F46. Narrow quartz-pyrite-magnetite vein (lower center of image) surrounded by a chlorite (dark green)-hematite alteration halo. Remnant spherules of the host volcanic rock are visible at the top left and top right of the image (interval 193-1188A-12R-1, 123-124 cm, Unit 10, in plane-polarized light; width of view = 1.4 mm. Photomicrograph ID# 1188A_67; thin section 11).