Iron ore is also racing ahead of coal and is tipped to have generated more than double the latter's revenue in the last quarter of 2013.

The mining investment boom is generally considered to have peaked in Australia, but export earnings and the contribution to public revenue are not declining yet, according to East & Partners' iron ore and coal (IOC) index.

It forecasts that Australia stands to earn $US21.9 billion ($24.53 billion) from booming iron ore exports during the last three months of 2013, compared to softening thermal and coking coal revenues of $US10.1 billion.

Based on figures from Australia's export ports and official government data, the report predicts the 7.9 per cent revenue lift from the previous quarter will come from a 6.3 per cent lift in iron ore exports to an all-time high of 161 million tonnes. The iron ore price was 1.3 per cent higher at $US136 a tonne during the period.

While coal's shipments are also higher, that is not expected to be enough to offset a price that continued to fall during the quarter while costs remain high.

Thermal coal shipments are tipped to have risen 3.1 per cent to 50.1 million tonnes on the back of a strong performance at the port of Newcastle, in NSW.

Revenue is tipped to have fallen half a per cent to $US4.02 billion. Metallurgical coal exports is expected to have trended 3.3 per cent higher to 44.1 million tonnes. However, a 3.4 per cent lower average price of $US140 a tonne is tipped to cause revenue to fall 1.6 per cent to $US6.1 billion.

Less than five years ago, coal was Australia's biggest export earner ahead of iron ore but faces strong global competition and has been hit by mass job losses.

East & Partners' senior markets analyst Martin Smith viewed the latest forecasts as good news for both the iron ore and coal industries.

The two industries had shifted from greater capital expenditure in capacity and efficiency improvements to outright production, with iron ore producers such as Rio Tinto, BHP Billiton and Fortescue Metals investing heavily.

``The majority of industry analysts expected growing iron ore stockpiles and declining Chinese economic growth to drag on iron ore prices, however this has not eventuated,'' Mr Smith said.