Altamira Gold (TSXV: ALTA) has released an updated mineral resource estimate for its Maria Bonita porphyry gold deposit in Brazil’s Mato Grosso state, lifting contained gold by 82% from the maiden estimate published in May 2025.
The updated open-pit resource is reported at a 0.24 g/t gold cut-off. Highlights from the estimate incluide:
- Indicated resources of 25 million tonnes grading 0.50 g/t gold, containing 403,877 ounces of gold
- Inferred resources of 70 million tonnes grading 0.41 g/t gold, containing 908,477 ounces of gold
Most of the growth came in the inferred category, where contained ounces rose 150%. Indicated ounces increased 12%, while total tonnage climbed 90%. The comparison isn’t strictly like-for-like, as the maiden estimate used a lower 0.2 g/t gold cut-off.
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At a 0.5 g/t cut-off, a higher-grade portion of the deposit totals 9.30 million tonnes at 0.75 g/t gold for 225,630 ounces indicated and 11.11 million tonnes at 0.80 g/t gold for 286,859 ounces inferred.
The resource is constrained within an optimized pit shell with a waste-to-mineralized material ratio of about 0.4:1, using a gold price of US$3,300 per ounce. The estimate incorporates 3,868 metres of drilling across 11 holes completed since the maiden resource.
Gold at Maria Bonita is hosted in intrusive rhyolite porphyry and surrounding tuffs, with little associated sulphide and no significant base metals or deleterious elements. The highest assay within the resource to date is 1 metre of 7.27 g/t gold, reflecting a deposit defined by consistency rather than high-grade spikes.
“Gold mineralization at Maria Bonita continues to be uniform over wide intervals, both within and outside the confines of the porphyry intrusive,” said CEO Mike Bennett. “Our recent surface mapping has also identified a continuation of the porphyry system to the west, providing an important target for ongoing exploration.”
The deposit remains open to the west, south and at depth. Step-out drilling is now underway on the western extension, which falls within 58 square kilometres of newly accessible ground on the company’s 280 square kilometre concession.
Maria Bonita lies roughly 7 kilometres from the Cajueiro Central deposit, which hosts 185,000 ounces of indicated gold at 1.02 g/t and 515,000 ounces inferred at 1.26 g/t. The district is road accessible with grid power and local water supply.
Altamira Gold last traded at $0.29 on the TSX Venture.
