There is an old army rumour that South African infantry men were fed copper sulphate ("blouvitrioel" in Afrikaans) to decrease their libido, but it's not true:

There is an old army rumour that South African infantry men were fed copper sulphate ("blouvitrioel" in Afrikaans) to decrease their libido, but it's not true: https://samilhistory.com/2017/10/17/blue-stone-debunked/ https://samilhistory.com/2017/10/17/blue-stone-debunked/