Its shares touched a 52-week high of C$3 on the news intraday, before easing to close up more than 5% to $2.80.
A Phase III drilling programme is underway at the property in Sonora with a planned end of July cut-off for inclusion in a resource update.
CEO N. Eric Frier said the confirmed discovery of continuous, high-grade mineralisation in the Granaditas Vein increased the near-surface, high-grade footprint in the district.
He said the company had received an historic map from a local rancher last year that showed the location of the Granaditas mine, operated in the early 1800s, that had since been documented as "a lost Spanish mine".
The company then drilled below the 90-foot mark where historic miners had encountered water, and intercepted high-grade mineralisation using the same geological controls as other high-grade veins in the district, Frier said.
The headline intercept comprised 1.8m at 12.14g/t gold and 1,440.3g/t silver.
SilverCrest said it had also identified an un-named hanging wall vein about 40-80m to the southeast of Granaditas and is planning further drilling to test this area and more of the 23 known veins in the coming months.
It had announced a maiden inferred resource in February of 62.8 million silver-equivalent ounces, using a 150g/t AgEq cut-off.
The Vancouver-based company added to its cash and equivalents of C$6.5 million (US$5 million) at the end of March with a $17.2 million (US$13.2 million) equity raising at $2.10 per share that closed in May.