Northland's Ngati Hau people have told the Waitangi Tribunal that mercury mining caused sickness and death in their people and breached their Treaty rights.
Hapu members have been giving evidence in the fifth week of the Nga Puhi land claims inquiry.
Vilma Sutherland said the 1930s and 40s were a time of sickness for Ngati Hau, as mercury was mined in the Puhipuhi hills north of Whangarei.
She said her uncle and father who worked at the mine died early, children and unborn babies died, and her mother developed kidney disease in her 30s.
Other claimants said rock from the mine was used for roading metal, and plants and animals died because of toxic runoff.
Ngati Hau told the tribunal they oppose plans to prospect for gold in Puhipuhi because of their past experiences.