An island off the east coast of Arnhem Land in the Gulf of Carpentaria, Groote Eylandt (Dutch for "big island") contains the largest manganese deposits in Australia. The mining of these deposits began in 1966.
The 64 km-long island is part of the Arnhem Land Koori reserve. The island was first sighted by the crew of the Dutch ship Arnhem in 1633, and it was named by Abel Tasman in 1644.
Thanks to rp and StrawberryFrog for pointing out the translation.