Mithril is to acquire private company Sun Minerals, with owners of Sun including Leitch to end up with 40% of the ASX-listed junior and management.
The 40% stake also takes into account a A$4.9 million rights issue that will price new shares at 1c each.
Sun has an option to acquire ground making up the high-grade Copalquin tenements for a staged consideration including expenditure of US$8 million and a cash payment of $10 million (or issue of shares) by August 2023.
The Copalquin prospect is said to cover the entire Copalquin Mining District within the gold-silver trend of the Sierra Madre Occidental mountain range in Durango State, western Mexico.
According to Sun, the gold silver trend is host to numerous gold and silver deposits, with multiple producing mines including; Coeur Mining's Palmarejo, Agnico Eagles' Pinos Altos, Goldcorp's El Suazal Mine (now depleted), First Majestic Silver's San Dimas mine, Fresnillo's San Julian and La Cienega mines and the now closed Ocampo mine.
Sun was founded in 2017 and is said to have has thus far spent A$2.5 million on exploration.
Other involved in Sun include John Skeet, Hall Stewart and Garry Thomas.
Leitch, who will be appointed Mithril's executive chairman, was the non-executive director and major shareholder of Mexico focused Bolnisi until its $1.3 billion take-over by Coeur in 2007.
A 4500m diamond drilling program at Copalquin is planned upon deal completion.
Mithril listed in late 2002, with outgoing MD David Hutton having been with the company since early this decade.
Shares in Mithril more than doubled in early trade to 1.8c, capitalising the company at $9 million.