* Miners estimate resource at 5.6 mln oz gold equivalent
* They see pre-feasibility studies commencing in July 2010
* Gold Fields holds 51 pct, Buenaventura 49 pct in JV
(Adds Buenaventura CFO comments, shares closing up, byline)
By Teresa Cespedes
LIMA, May 11 Buenaventura (BVN.LM) (BVN.N) and Gold Fields Limited GFJ.J have found a major gold deposit in their Chucapaca project in southern Peru, near the border with Chile, the companies said on Tuesday.
The Canahuire deposit, which is inside the Chucapaca project area, has a mineral resource estimate of 5.6 million gold equivalent ounces, Buenaventura said in a media release.
South African miner Gold Fields has a 51 percent stake in the Chucapaca joint venture, while Peru precious metals miner Buenaventura holds the remaining 49 percent.
In a joint statement issued on Tuesday the companies said the "very promising gold discovery" represents a very important growth opportunity for Gold Fields and Buenaventura.
Shares in Buenaventura at the Lima stock exchange gained 7.6 percent in Tuesday's session.
"We've got to carry out environmental impact and feasibility studies before we start looking at details regarding how much we need to invest to start production," Buenaventura Chief Financial Officer Carlos Galvez told Reuters.
Galvez said the site's estimated mineral resources could increase, as the joint venture company is carrying out further exploration in adjacent areas.
"We hope the deposit is bigger than what we've got at the moment, and when we carry out the scoping study we'll have a better idea of the size of the project, (projected) output capacity, whether we need to do an open pit mine or how we do it," he said.
The statement said the companies could commence pre-feasibility studies in July 2010.
Canahuire also holds significant resources of silver and copper, the statement said.
Buenaventura CEO Roque Benavides told Reuters last week that the company expects to produce 1.1 million ounces of gold and 17 million ounces of silver this year. [ID:nN06137920]
Buenaventura had a net profit of $593.6 million in 2009, a 287 percent increase from a year earlier.
Gold Fields is the world's fourth largest gold miner. (Additional reporting by Ursula Scollo; Writing by Eduardo Garcia; Editing by Lisa Shumaker)