IRIS Metals (ASX:IR1) has completed its Phase 1 diamond drilling at the Tin Mountain Project, confirming high-grade lithium and caesium mineralisation.
Intersections include TDD-24-008 with 5.2m @ 2.05% Li2O from 39.2m, including 1.5m @ 3.04% Li2O from 40.8m, and TDD-24-007 with 1.0m @ 1.54% Cs2O from 31.2m.
The drilling confirms the pegmatite extends down-dip under cover, remains open at depth, and has lateral mineralisation near the surface.
Phase 2 will target deeper core pegmatite zones using advanced horizontal drilling technology, complemented by mineralogical mapping to support a maiden mineral resource estimate.
A total of 23 diamond drill holes, totalling 1,122m, were completed in late 2024, with core logging and sampling conducted at IRIS’s Custer facility and assays processed by SGS.
Despite challenges from historical underground workings, Phase 1 drilling confirmed near-surface lateral mineralisation and pegmatite continuity at depth.
The historic mining cavern and surrounding areas, which conventional surface drilling could not fully test, will be a priority for Phase 2 exploration.
IRIS is preparing for the 2025 field season, with drilling planned across its Beecher, Tin Mountain, and Edison projects, alongside a large-scale airborne geophysics program refining targets within its extensive South Dakota exploration package.
The Tin Mountain Project, located 10km from Custer in the Black Hills, sits on private land under an IRIS option agreement and includes the historic Tin Mountain mine, first claimed in 1889 and intermittently active through the 1950s.