Since acquiring the Sandstone Gold Project in 2016, the company has compiled and reviewed a large legacy database ahead of a series of focused exploration and drilling campaigns.
Alto’s goal is the delineation of a plus-1 million-ounce JORC mineral resource that could become the basis for the re-establishment of standalone oxide and primary gold mining and milling operations.
Forward plan for near-term opportunity
The company’s plan is to increase its gold resource incrementally targeting shallow deposits (about 200 metres below surface) at the Vanguard, Indomitable, Lord Nelson and Lord Henry deposits that can be economically mined.
Alto has already defined a gold resource of about 4.9 million tonnes at 1.7 g/t for 261,000 ounces of contained gold at the Sandstone Gold Project.
This includes the maiden inferred resource of 124,000 ounces of gold for its Indomitable and Vanguard Camp deposits.
Alto managing director Dermot Ryan recently said: “These shallow gold deposits in the Vanguard and Indomitable Camps all have a gold rich lateritic cap overlying the oxide gold mineralisation, most are “blind” in that they are buried under alluvium, and most importantly, the gold grades increase with depth into the transition and fresh rock zones.
“Now that we understand the structural controls on these deposits, the next stage is to RC (reverse circulation) drill test them (and their associated bodies) along strike and down plunge, where extra ounces of gold can be rapidly added.
“When Alto purchased the project in 2016, there were no JORC 2012 mineral resources.
“With carefully targeted drilling and adequate funding, there is potential to double the current JORC 2012 mineral resource base to +500,000 ounces over the next 12 months.”
Sandstone Gold Project gold resources
In October 2018, Alto confirmed the geological models for the Vanguard and Tiger Moth prospects.
An RC drilling program consisting of two holes recovered high-grade intercepts from each prospect, as well as providing samples for further metallurgical test work.
The drill hole at Vanguard intersected 40 metres at 3.5 g/t gold from 60 metres, including 12 metres at 5 g/t from 60 metres, while Tiger Moth hole intersected 8 metres at 4.1 g/t from 52 metres.
Understanding high-grade plunging shoots of orogenic gold systems is the key to unlock potential multi-million ounces gold deposits
Alto managing director Dermot Ryan added: “Alto’s recently published mineral resource estimate for the Indomitable and Vanguard camps was the result of applying a systematic exploration approach.
“This process resulted in the selection and successful testing of a number of litho-structural gold targets.
“The next stage is to step-out and drill test the down-dip/down-plunge extensions of these newly discovered mineralised structures and convert gold mineralisation into mineral resource.”
Alto plans to conduct RC and diamond core drilling at Vanguard and Indomitable to define the extent of the mineralised structures, as well as aircore drill testing of soil and laterite gold geochemical anomalies.
The company will also progress its resource evaluation work, which will include:
• Maiden mineral resource estimation for Ladybird, Havilah and Sandstone North using existing available data;
• Update to the company’s JORC 2012 mineral resource inventory; and
• Geotechnical drilling, bulk density measurements and metallurgical test work where required to convert gold mineralisation into mineral resource.
Alto’s medium to long-term goal is to discover 5 million ounces gold in high-grade deposits (200 – 500 metres below surface), which will serve as the foundation of major mining operations.