Australia is entering stage three of the resources boom. Mineral exports rose 11 per cent in the March quarter, while imports of specialised construction machinery used for mining investment fell sharply.
The Bureau of Statistics reported a dramatic $5.6 billion lift in Australia's trade balance in the March quarter. Rising exports and falling imports delivered a small $367 million surplus, up from a $5.2 billion deficit in December.
Mining was most of the story. After seasonal adjustment, exports of iron ore and other metals rose by $2.2 billion or 11 per cent - and imports of miscellaneous capital goods fell by $1.1 billion or 26 per cent.
The bureau estimates that in the six months to March, imports of construction machinery fell by 44 per cent year on year. Most of this is used in mining investment.
At face value, the figures suggest that in Professor Bob Gregory's model of the resources boom, Australia is moving from the second to the third stage: from mining investment to mining exports.
In March alone, despite big falls in most mineral prices, mining exports rebounded to $14.85 billion, their best month in almost a year. The bureau will reveal next week how much of this was in volume, and how much in price.
The Bureau of Resource and Energy Economics forecasts that the volume of resource exports will grow 28 per cent in the next five years, as the investment pipeline gradually comes on stream.
But the March quarter growth in seasonally adjusted mining exports could overstate their real strength. This summer was free of the cyclones which severely disrupted mining exports twice in recent summers, inflating seasonal adjustment factors. Last year, seasonally adjusted March quarter exports of metal ores and minerals fell 13 per cent.
The volatile iron ore price also spiked in the March quarter. It has fallen 20 per cent since, suggesting that the June quarter export earnings will fall back.
But the import figures add to evidence that the mining investment boom is winding down more quickly than anticipated. The boom saw imports of specialised machinery become Australia's third-biggest import category. By March, they were back among the also-rans, falling behind pharmaceuticals, computers and others.
Economists fear Thursday's capital expenditure survey will forecast lower capital expenditure in 2013-14. Westpac senior economist Andrew Hanlan cautioned that whereas the forecast usually swells between December and March, this time it could shrink.
"We see the risks as skewed to the downside," Mr Hanlan said. "Mining is increasingly focused on cost-cutting, and the initial estimate for services appears to be overly optimistic."