The included mineralogical reports and explanatory prior company correspondence give the results of, and rationale behind, a lengthy programme of mill product sampling and sample description for weekly to monthly process monitoring throughflow samples taken from the Cattlegrid pit copper ore processing flotation plant. The microscopic mineral grain composition of plant feed and tails and of the final ore concentrates is described semi-quantitatively, based on visual estimation of mineral abundances, and additional comments are given on sulphide mineral intergrowth relationships likely to affect the optimum liberation of critical minerals, including those carrying significant zinc and cobalt values.