Lancair is essentially correct. That's a good get from memory, and not an altogether easy one to find on Google with the clue I provided.
1530-36. The Dauphin Chart (a map of Australia, date 1530-36), which is preserved in the British Museum, and which is believed to have be reproduced from earlier Portuguese charts, makes it appear probable that the occurrence of gold in Australia was known to the Portuguese and Spaniards more than 350 years ago, for the north-western coast is named on this chart Casta DOuro (Gold Coast).
This extract is taken from Gold, Bulletin No. 7, Department of Mines Geological Survey, Alfred James Kent, Sydney, 1924, by E.J. Kenny.
pp.5-9.
However, it is a long bow to draw, as I don't think there are many gold rich areas on the coast of WA where the early explorers may have landed.
Anyway, over to Lancair.