With the rainy season petering out, mining companies are gearing up to resume full operations on prospects in northern and eastern Cambodia, with investors keeping a close watch as firms push to expand their resource estimates and the country prepares to open its first royalty-bearing commercial mine.

Australian mining firm Renaissance Minerals raised $1.7 million in an equity placement during the off-season and is preparing to resume exploratory work at its Okvau gold project in Mondulkiri province. The company estimated a 1.2-million ounce resource at the site last season and will begin surveying gold mineralisation extending beyond the resource envelope this month.

“We still see a lot of potential exploration-wise to grow out the resource at Okvau,” said Justin Tremain, Renaissance’s managing director.

The firm’s scoping study estimates that the project’s mineral resource is sufficient to support annual production of 93,000 ounces of gold over an approximately eight year mine life.

The initial capital expenditures are estimated at a relatively low $133 million on account of the project’s high-grade ore body, which has put its all-in sustaining cost (AISC) below $800 per ounce – enough for a nice margin even with today’s depressed gold prices.

Falling gold prices, however, prompted Renaissance to seek a new arrangement with Australian firm OZ Minerals, from which it purchased the project in 2012 in exchange for A$18 million, shares, and additional milestone payments if the ground were developed.

“Back then, the economic environment for gold projects was a lot better than it is now,” Tremain said. “Times are more challenging now.”

Renaissance reached an agreement with OZ Minerals in August to swap A$22.5 million in outstanding deferred milestone payments for a capped 1.5 per cent gross smelter royalty. The restructured deal better reflects lower gold prices, allowing development to move forward, according to Tremain.

Renaissance has commissioned an environment and social impact study (ESIA) for the Okvau site, but it could be years before the company draws its first ounce of gold.

“We’re looking to complete the feasibility study and develop the project ourselves,” said Tremain, “but we’re somewhat beholden to how the regulatory environment evolves, for approvals and financing.”

Further north in Ratannakiri province, Angkor Gold has just resumed exploration work on its Okalla West and Halo prospects.

Geophysical surveys of these prospects will help define the size and scale of their mineral resources.

Meanwhile, Indian mining firm Mesco Gold is in the final stages of preparation to begin production at Phum Syarung, a gold mine purchased from Angkor for $1.2 million in 2013 that is set to become the Kingdom’s first royalty-generating mine. Angkor retains a net smelter royalty agreement to the site that would see it receive a share of any gold extracted.

John-Paul Dau, vice-president of operations at Angkor Gold, said Mesco had completed the necessary licensing procedures including a feasibility study and environmental impact assessment, and a final mining permit was expected by the end of the year.

“The first gold will be [drawn] in early 2016,” he said. “But it’s going to take time before you’re moving into full production, probably 18 months.”

Angkor Gold, with seven exploration licences in Cambodia covering 1,500 square kilometres, has entered negotiations with several potential partners looking to acquire interests in its tenements.

“I think by next year, or even sooner, we could have a deal where somebody comes in,” said Dau. “We would be the operator on the next deal though.”

Gold is sexy, but the most significant plays in Cambodia could well be base metals such as copper and molybdenum. And in Preah Vihear province near the Thai border, one mining outfit thinks it may have hit upon a major find.

Australian mining firm GeoPacific Resources, operating through a joint venture with the Royal Group, claims it has found high-grade copper deposits on the 158 square kilometre tenement in purchased in 2013, with significant gold mineralisation to boot.

The company said in a disclosure statement this week that it plans a maiden resource and scoping study this season, with ongoing exploration aimed at increasing the scale of the project and understanding of its geology.

Mekong Minerals, an unlisted Australian junior mining firm, stepped up its investment in Cambodia in June by completing its full acquisition of ASX-listed Southern Gold’s local subsidiary in exchange for a free carried interest and royalty.

Together, the two firms have invested approximately $12 million in tenements spanning 1,500 square kilometres, according to Anthony McClure, Mekong’s managing director.

He said exploration work had uncovered “considerable areas of gold mineralisation that require further substantial investment,” and survey work would continue this season.