• Phase II drilling at Tin Mountain Project confirmed significant high-grade lithium and critical minerals mineralisation
• Results highlight Tin Mountain's strategic importance to national supply chains with no current U.S. rubidium production
• IRIS is evaluating the multi-commodity critical mineral potential of Tin Mountain and will target a JORC-compliant maiden Mineral Resource Estimate in Q1 2026

IRIS Metals Ltd announced exceptional drill results from its Phase II program at the Tin Mountain Project in South Dakota's Black Hills, confirming high-grade lithium mineralisation and revealing significant multi-element potential in the host pegmatite, including beryllium, caesium, rubidium, and tantalum. The strategically executed eight-hole program delivered outstanding efficiency, with drill core assays yielding some of the highest-grade intervals for several critical minerals ever reported in the United States. These results position IRIS to advance its vision of developing a premier critical minerals hub in this world-class pegmatite district. The deposit features a shallow weathering profile, with promising untested extensions to the north and east, signaling additional resource potential. Notably, rubidium, a United States Geological Survey (USGS) listed Critical Mineral, has no current U.S. production, underscoring Tin Mountain's strategic importance. IRIS is advancing the maiden mineral resource estimate for Tin Mountain, covering both lithium and rubidium, with delivery expected in Q1 2026. Additional critical mineral commodities, including beryllium, caesium, and tantalum may be added to the MRE if warranted.

IRIS is evaluating the multi-commodity critical mineral potential of Tin Mountain and will target a JORC-compliant maiden Mineral Resource Estimate for lithium and rubidium, and potentially other critical minerals, in Q1 2026.