Golden Swan was first discovered in the wider Southern Terrace area in April 2020, and has been a key focus for drilling ever since.
It was initially described as "something very exciting", and after past 18 months of work Golden Swan has a sense of scale: 160,000 tonnes grading 3.9% nickel for 6250t nickel in indicated and inferred resources.
The indicated resource that could be recovered from the Silver Swan decline is 5200t grading 4.7%, within 111,6000t.
It increases the scale of the prize at Black Swan by about one third, to 15,330t at 7% nickel.
Managing director Peter Harold said Golden Swan's maiden resource represented a significant development in the progress towards restarting operations at Black Swan in late 2022.
Mine studies have commenced, which should allow maiden reserves to be declared.
Golden Swan is just 120m from the drill drive, with Harold saying it could be developed relatively quickly.
Poseidon announced a new ‘fill the mill' strategy in September, and is running a bankable feasibility study.
Golden Swan sits on the Southern Terrace, which is 450m south of the Silver Swan decline, and has been tested with 69 holes for 22,000m since discovery.
Poseidon is operating two rigs underground, and while recent exploration of other Southern Terrace targets such as Peking Duck and Fledgling-Canard, and electromagnetic surveys along the Southern Terrace, testing up plunge of Golden Swan, failed to detect significant anomalism, the company believes the Southern Terrace remains a prospective target.
The rigs are now focused on resource definition drilling program down plunge of Silver Swan.
Poseidon's new strategy is to refurbish and restart the Black Swan concentrator at a stepped down 1.1 million tonnes per annum.
A final investment decision is targeted for May 2022.
The company has also started examining the potential of its mines to supply feed to a battery material refinery hub in Kalgoorlie being studied by Pure Battery Technologies.
Poseidon has remaining cash of $29 million.
Shares in the company have traded between 5.5-16c over the last year. The stock closed at 10.5c yesterday, valuing Poseidon at $322 million.
