TROY, Mont. - Exploratory core drilling has indicated that higher-grade silver and thicker veins of minerals exist in areas 1,120 feet below current Troy Mine operations, a finding that could eventually double the mine's current six-year plan, officials said.

"There had been nice intercepts of minerals over the years but in this, there has been some higher than normal" concentrations, said Tim Lindsey, chair of the board of directors for Revett Minerals, which owns Troy Mine. "If the project is big enough, if it would add another three to four years to the mine life, it would certainly be economically" feasible to pursue.

The latest samples indicate significantly higher silver concentrations. One area revealed 1.99 ounces per ton, double the level of what current operations yield.

Previous mineralized sections taken during exploratory drilling from the area known as the I-Beds have averaged 30 feet in width, but the most recent drilling has discovered a 95-foot section, thicker than any other sample taken from the I-Beds to date.

Mine officials hope that more exploration will reveal that silver and copper deposits link the I-Beds beneath the current mining area with the previously-identified JF deposits, located about 8,000 feet south of current operations.

Going after the 11 million tons of minable ore identified at the JF Properties is not cost-effective, Lindsey said, unless it is linked to a mine that already has established infrastructure.

Revett plans to step up its exploration program.

"Based on our increasing confidence in delineating a significant resource in the I-Beds, we are looking to accelerate the exploration efforts," said John Shanahan, Revett's chief executive officer. "We believe continued exploration success ... will add significantly to Troy's mine life and facilitate the eventual development of the JF Properties to the south."