The initial investment in Scotgold, which has a dual listing in Australia and the UK's junior Alternative Investment Market amounts to just A$200,000 (£118,000).
But the deal makes Zio the single largest shareholder in Scotgold with a stake of around 4.5% and comes with an indication that further money could follow.
Scotgold said: "Scotgold has agreed to give Zio a non-exclusive right to conduct due diligence enquiries into Scotgold and the Cononish Project with a view to Zio making further investments in Scotgold, subject to any relevant shareholder or regulatory approvals."
A spokesman for Scotgold confirmed that Zio Holdings is an investment fund but said he could not provide the names of those behind it.
However, documents filed by Australia-based Luiri Gold, which has mining interests in Zambia, suggest that it established Zio as a subsidiary in 2008.
The funds from the share sale are just a fraction of the £22 million that Scotgold has said it needs to develop its site in the Loch Lomond and the Trossachs National Park. The money will keep cash-strapped Scotgold going for a period and indicates that Zio is confident enough to put some funds at risk while it continues its discussions with Scotgold's managers.
Scotgold's shares rose 0.2p or 14.3% in response to the news, closing at 1.6p.
After overcoming objections from environmental groups, Scotgold secured long sought after planning permission for its mine in 2011.
Scotgold expects to recover a total of 121,800 ounces of gold and 469,700 ounces of silver from the Cononish mine near Tyndrum.
But its development plans have been hit by a decline in the gold price, which cut the amount of funding likely to be provided by South African lender RMB Resources, which was linked to the price of the previous metal.
This has left Scotgold trying to obtain finance from new investors at a time when the sector has become less attractive.
It put its plans on hold in May and told investors it was ending all discretionary expenditure.
In its final development study for the Cononish mine published in April, Scotgold said at prevailing prices it could expect £39.8m of pre-tax cashflow over the mine's seven-year life.
This would allow it to pay back development costs 26 months after the start of production.