Accurate prediction of environmental issues from pre-emptive rock studies is the aim. Successes are heart-warming, but the lessons (best not to call them failures) can be most instructive, and this webinar will cover both. Southern NZ has 150 year history of gold mining, both placer and hard-rock. The biggest issue for placer mining has always been downstream suspended sediments. This issue is affected by geology and is partly predictable and manageable, but subtle features can lead to large negative effects.