Figure F16. Altered dacite wallrock fragment (top) containing abundant pyrite, with a thin quartz filled fracture extending from the jasperoid host in Sample 193-1189B-11R-1 (Piece 3, 14–16 cm; CSIRO 142714). Pyrite is also common in quartz to the left of the fragment. Birefringent anhydrite fills a former drusy cavity. This sample does not contain selvages of inclusion-free quartz at the margins of wallrock fragments. Width of view = 1.3 mm. A. Ordinary light. B. Crossed polarizers.

Figure F16. Altered dacite wallrock fragment (top) containing abundant pyrite, with a thin quartz filled fracture extending from the jasperoid host in Sample 193-1189B-11R-1 (Piece 3, 14–16 cm; CSIRO 142714). Pyrite is also common in quartz to the left of the fragment. Birefringent anhydrite fills a former drusy cavity. This sample does not contain selvages of inclusion-free quartz at the margins of wallrock fragments. Width of view = 1.3 mm. A. Ordinary light. B. Crossed polarizers.