It said recent diamond drilling had resulted in a reinterpreted geological model for the four deposits, improving confidence and "providing a more robust framework for the study and for future exploration".

The project's indicated resource now stands at 3.4 million tonnes at 299.8g/t silver for 32.9 million ounces, and an inferred 1.28Mt at 277g/t for 11.4Moz.

The 2015 resource had comprised an indicated 3.07Mt at 321.6g/t for 31.8Moz, and an inferred 0.9Mt at 373.3g/t for 10.8Moz.

The past-producing property is said to have produced more than 20Moz of silver and the company said Dolly Varden was among the richest silver mines in the British Empire 100 years ago.

President and CEO Gary Cope said the update and preliminary testwork were important steps in the project's advancement.

"The programme's metallurgical testing, yielding 86.9% for Torbrit and 85.6% for Dolly Varden, supports the historical results and demonstrates that the silver can be extracted from Dolly Varden styles of mineralisation through conventional processes," he said.

The company has cash of about C$2 million (US$1.5 million), according to a presentation this week.

Its shares closed down 1.6% to 31c yesterday, near a 52-week low and half the value of 12 months ago.

At that price, Dolly Varden Silver's market capitalisation is $17.8 million.

The silver price is about 10% lower than a year ago, worth US$14.81 an ounce on the spot market.