Altamira Gold Announces Significant Increase in Mineral Resources at the Maria Bonita Porphyry Gold Deposit, Cajueiro District, Brazil
Message from the CEO
Hi Everyone
Today we have announced an important update to the open-pit Mineral Resource Estimate at the Maria Bonita Porphyry Gold Deposit, one of two established gold resources within our Cajueiro District. The updated resource has been extended to total indicated Resources of 25Mt@ 0.50 g/t gold (403,877 oz contained) and Inferred Resources of 70 Mt@ 0.41 g/t gold (908,477 oz contained).
It’s worth putting Maria Bonita into the broader context of the Cajueiro District. Maria Bonita is located approximately 7km west of the Cajueiro Central deposit, which has an existing NI43-101 resource of approximately 700,000 oz of gold, comprising 185,000 oz of Indicated Resources at 1.02 g/t gold and 515,000 oz of Inferred Resources at 1.26 g/t gold. That resource was established in 2019 using a gold price of US$1,500/oz. Together, these two deposits demonstrate the significant scale already defined within the Cajueiro District, while numerous additional exploration targets remain to be tested. Mike´s comments are as follows;
1. The new resource represents a very significant increase from the maiden resource published just over a year ago, in May 2025. We have increased the Inferred gold resource by 150% to 908,477 ounces at 0.41 g/t Au, while the Indicated gold resource increased by 12% to 403,877 ounces at 0.50 g/t Au.
2. It is important to put this increase in perspective from the exploration standpoint. The new resource was completed using data from an additional 11 drill holes with a total of 3,868 metres drilled in this third campaign of diamond drilling at Maria Bonita. This gives us exceptional drilling success parameters with 153 ounces of total estimated gold generated per metre drilled. This metric is possible at Maria Bonita because of the extremely consistent distribution of gold mineralization within the porphyry style of mineralization, both within the porphyry itself and in the quartz veined wallrocks.
3. The average grade of our updated Mineral Resource Estimate is 0.41 g/t gold in the Inferred category and 0.50 g/t gold in the Indicated category.The average grade of the new resource is 0.43 g/t gold which is the same as the head grade at the Paracatu mine, Brazil’s largest gold mine, owned and operated by Kinross.
4. Another important parameter to take into account is the higher- grade central core of our Maria Bonita deposit. At a cut-off grade of 0.5 g/t gold, this Mineral Resource comprises 512,490 ounces at an average grade of 0.78 g/t gold, including 225,630 ounces at 0.75 g/t gold in the Indicated category and 286,859 ounces at 0.80 g/t gold in the Inferred category.
5. We should also note that the updated Mineral Resource model is mineralized from surface soil down to some 400 metres in depth with a very low waste to ore ratio of 0.4:1 for an open pit mining scenario. The resource is also open in various directions both at depth and importantly to the west. We have recently identified a new porphyry body, Maria Bonita West (see press release 25 August 2026) where we will start drilling this week.
6. The metallurgical tests we have carried out to date on the mineralized core show that +90% of the gold can be recovered from the hard rock by agitated cyanide leach methods with an extremely low cyanide consumption. This is an extremely important technical parameter from an economic perspective and further metallurgical tests will be carried out to better understand the recovery levels of the enlarged Mineral Resource.
7. Finally, Maria Bonita benefits from an existing infrastructure base that could support a potential mining operation. Grid electricity is available from a nearby hydroelectric plant approximately 15 km from the resource, while the Company owns the 409-hectare farm that covers the vast majority of the updated Mineral Resource. The Company has also built a camp approximately 2 km from the deposit. We are located 1.5 hours by road from the city of Alta Floresta in the north of the state of Mato Grosso, where we have administrative offices and where all food, fuel and exploration supplies are sourced. The combination of a large, shallow and open-pit resource, strong metallurgical performance and existing infrastructure provides a solid foundation for the next stage of work at Maria Bonita.
Please do not hesitate to contact Mike directly at mbennett@altamiragold.com should you have any questions.
Best regards,
Altamira Gold Team
