The mining consultant of Surbiton Associated doubts the Greens' estimate of the Australian gold industry in relation to how much the mining tax would generate if it would to apply to the gold industry.

"It is easy to assume that because of high gold prices, every gold mine in Australia is making massive profits, but that is not the case," Surbiton Associated consultant Dr. Sandra Close said.

"Some are enjoying excellent returns. However, others are struggling," said Ms Close, who described the Greens' estimate as highly suspect and quite misleading.

According to the Greens, the inclusion of gold in the mining tax would generate at least $1.8 billion in revenue over 10 years.

"Gold is traded on international and local markets. To suggest it can't be taxed because it is mined with other minerals is simply not right," Australian Mining quoted Adam Bandt of the Greens.

Ms Close rejected the Greens' push for the expansion of the mining tax beyond iron ore and coal.

"I am all in favour of Australia and Australians getting a fair return for our mineral wealth but, in setting government policy, it is essential to get the basic facts right and take account of the huge variability of the mining industry," Ms Close said.

She said that based on Surbiton's production survey for the September quarter, the three largest mines produced a total of 515,229 ounces, with Super Pit accounting for 37.3 per cent, Boddington for 32.2 per cent and Telfer 26.6 per cent. Total output was worth $3.8 billion at current spot prices.

The consultant disclosed that the gold industry failed to fully capitalise on record gold prices in the quarter which caused production to dip 2.2 per cent from the previous quarter. However, Ms Close hinted the slippage may have been deliberate because lower production allowed a more effective use of gold resources.

By opting to mine ore with less gold as bullion prices went up $3.5 billion, some Australian miners preserved the richer ores in case prices tumble.

For the same quarter, gold prices in the U.S. reached an all-time record afternoon fix of $1,895 an ounce in early September and averaged $1,702.