This specimen is probably the most interesting rock that I have collected It was collected in the vicinity of the hill top wind farm near Llandinam. just a couple of miles away.A zig-zag road was excavated in the hillside to create access to the summit of the hill, and this specimen was collected from the newly exposed cutting, at an elevation of about 500m. asl. It appears to be sedimentary rock that has been infiltrated by hydrothermal mineral rich fluid. About 90% of the original sediment has been replaced by silica in the form of tiny quartz crystals The other 10% is sediment which has been silicified There are traces of the original layers of sediment, and also some calcite deposits. A second specimen from the same location Is mostly calcite, with some quartz and is illustrated in the the next article.