The company said the third vein contained high-grade gold and silver, including 1.20m at 36.8g/t gold and 259g/t silver, within a wider 7.11m at 9.42g/t gold and 69.36g/t silver from 370.92m.
"The presence of high-grade mineralisation below 1100m elevation in the deeper third vein zone broadens the vertical range of such mineralisation at South Zone," exploration manager Peter Fischl said.
Westhaven announced a 20,000m drill programme in February, to follow up on its South Zone discovery last year which drew strong interest and sent its share price up 980% over 2018 to help put it at the top of the 2019 TSX Venture 50 list.
The company raised C$2.5 million (US$1.9 million) in a placement at $1.1325 per flow-through share in February to fund exploration at Shovelnose, one of its four projects in the Spences Bridge Gold Belt.
It had $1.27 million (US$0.95 million) in cash and equivalents at the end of June.
Its share price went from below 20c before its October discovery to a peak of $1.43 in December.
Westhaven gained 20% on Friday to close at $1.14, capitalising it at $102 million (US$76.6 million).