NEW YORK — Molycorp Inc. has announced a 36-percent increase in proven and probable reserves at its Mountain Pass rare earths mine in California.

Reserves are now put at 18.4 million tons of ore estimated to yield 2.94 billion pounds (1.3 million tonnes) of rare earth oxides, compared with a 2010 estimate of 13.6 million tons yielding 2.24 billion pounds (1.02 million tonnes) of oxides.

"I am pleased to see our world-class deposit continue to grow in size, and I believe that our ongoing exploratory drilling at Mountain Pass may show an even larger estimate of proven and probable reserves once that work is completed," Mark Smith, president and chief executive officer of the Greenwood Village, Colo.-based company, said in a statement.

Both estimates were developed by the Lakewood, Colo.-based branch of SRK Consulting.

Molycorp’s shares rose on the news, with the stock trading above $35 mid-morning on the New York Stock Exchange after opening at $33.48.