Difficult geology, coal quality issues and slow development rates have left Solid Energy questioning the economic viability of the mine, located in New Zealand's South Island north of Greymouth. The company was supposed to announce in July this year whether the mine would continue or be closed, but that announcement has since been delayed.

Engineering, Printing and Manufacturing Union mining spokesman Ged O'Connell told the Press (Christchurch) there had been significant dissatisfaction at the mine over the uncertainty.

“No news is good news, but for people trying to plan and determine their lives, it is just hopeless. When you think about the amount of money that's gone down that hole, they [Solid Energy] are very reluctant to say no," O'Connell said.

That uncertainty has driven eight miners and eight trades and technical staff to leave Spring Creek.

Since then, Solid Energy had recruited six miners and two geologists, bringing the workforce to 129 at the end of last month – 15 workers short of full numbers, the Press reported.

Currently Solid Energy is making one last ditch attempt to keep the mine open, exploring the feasibility of processing coal to produce a higher quality product for international thermal and steel making markets.

Solid Energy chief operating officer Barry Bragg said in May this year that the work would involve finalising a mine plan to access thicker coal seams, along with tests to confirm the feasibility of an upgrade of the coal washery to produce an improved product.

“However, we would need to have a high level of confidence that the international market would pay a premium for this higher quality product," he said.

Solid Energy was also completing a $NZ1 million mining feasibility study that includes some geological drilling to confirm the final mine design.