Sunstone Lifts Bramaderos Resource 72% to 6.2Moz AuEq

Sunstone Metals (ASX:STM) released an updated Mineral Resource Estimate for its Bramaderos gold-copper project in southern Ecuador, adding its 2026 drilling and a new deposit at Copete-Porotillo and lifting the Indicated share it needs for future studies.

The October 2026 MRE, prepared by independent consultant Exora Consulting, is 464Mt at 0.42g/t AuEq (0.29g/t gold, 0.10% copper and 0.9g/t silver) for 6.2Moz AuEq at a 0.3g/t AuEq cut-off, within a preliminary optimised pit shell. That is up 2.6Moz AuEq, or 72%, on the November 2025 MRE. Indicated Resources are 229Mt at 0.45g/t AuEq for 3.3Moz AuEq, which the company describes as a 450% increase, with Inferred Resources of 236Mt at 0.38g/t AuEq. The company attributes the increase to new Copete-Porotillo resources (1.3Moz AuEq), more drilling and trenching at Melonal (0.3Moz AuEq), and a deeper, larger pit shell reflecting that drilling, higher price assumptions and improved gold recoveries. AuEq uses US$3,000/oz gold, US$6.0/lb copper and US$40/oz silver. Sunstone also updated a Porphyry Exploration Target of 270 to 430Mt at 0.41 to 0.69g/t AuEq for 3.5Moz to 9.5Moz AuEq, in addition to the MRE.

The Exploration Target is conceptual, and the company says it is uncertain further exploration will result in a Resource. Metallurgical test work at Porotillo is ongoing, with lower recovery assumptions applied to transition material meanwhile. The release reports no Ore Reserve or development economics.