Figure F15. Euhedral growth structure defined by slight variations in refractive index and in places by minute fluid inclusions, in quartz grains within jasperoid Sample 193-1189B-11R-1 (Piece 3, 14–16 cm; CSIRO 142714). The two central quartz grains have distinct cores with abundant inclusions of tiny hematite flakes. Pyrite interstitial to quartz at the lower center possibly fills a former drusy cavity. Elsewhere in the sample, similar quartz grains project into open cavities. The spotty effect arises from the underlying ground surface, caused by use of a narrow aperture for the photograph. Width of view = 0.25 mm; ordinary light.

Figure F15. Euhedral growth structure defined by slight variations in refractive index and in places by minute fluid inclusions, in quartz grains within jasperoid Sample 193-1189B-11R-1 (Piece 3, 14–16 cm; CSIRO 142714). The two central quartz grains have distinct cores with abundant inclusions of tiny hematite flakes. Pyrite interstitial to quartz at the lower center possibly fills a former drusy cavity. Elsewhere in the sample, similar quartz grains project into open cavities. The spotty effect arises from the underlying ground surface, caused by use of a narrow aperture for the photograph. Width of view = 0.25 mm; ordinary light.