An option costing A$50,000 and will see Castillo take a close looked at tenure in NT (called Litchfield) next to Core Lithium's Finniss pre-development asset and ground in WA (called Picasso) "proximal" to Liontown's Buldania lithium resource.
If exercised, $1 million of Castillo's scrip will be issued to vendors.
Further scrip payments are due upon drilling and resource milestones.
Castillo raised $11.7 million in June for copper prospects in Australia and Zambia, with its "strategic intent (being) to transform into a mid-tier copper group".
Shares in Castillo were up 12% to 3.6c in morning trade, capitalising the company at $47 million.
The raising in June issued new shares priced at 4.2c each.
