The Australian federal government is facing a lawsuit over damage done to Indigenous land by a decades-old mining project.Gumatj leader Galarrwuy Yunupingu revealed on Saturday that he and his people were taking legal action against the commonwealth, seeking compensation for the loss of native title over the minerals exploited by mine operator Nabalco and its successor, Rio Tinto, as well as the destruction of key dreaming sites.The suit is expected to use the historic precedent set by the…