The value of Western Australia's mineral and petroleum production in the 2016 financial year slid 12% to A$87.5 billion, according to the state's Department of Mines and Petroleum.
The department said in its annual report, released Sept. 26, that the drop in value was attributable to steep price falls for many of the state's major commodities.
The value of iron ore sales fell for the second year in a row, coming in 11% lower at A$48.3 billion.
The drop-off in the value of iron ore sales led to a A$425.9 million fall in royalties received from Western Australia's most valuable commodity to A$3.60 billion. However, royalty income was actually better than the A$3.04 billion the government estimated it would receive in the 2016 financial year.
Going against the trend was gold, which notched a 10% gain in the value of sales to reach A$10.0 billion.
This was largely due to the increase in demand for gold as an investment asset, the Department of Mines and Petroleum noted.
Exploration for gold rose to A$275.3 million, outspending iron ore for the third consecutive quarter.
Gold royalties climbed A$24.8 million to A$250.1 million during the 2016 financial year.
Mineral sands was the only other commodity that netted the state government a positive gain at A$16.6 million worth of royalties received, compared to A$12.9 million a year earlier.
Overall, the Western Australian government lost A$480.8 million in royalty income compared to the prior year, with total royalties amounting to A$4.22 billion.
The government did, however, bank a higher income from lease rentals, which rose A$2.7 million year over year to A$91.6 million.