IRIS Metals Limited (ASX: IR1), an exploration company focused on pegmatite-hosted critical minerals, has announced significant rubidium assay results from its 2023 and 2024 drilling programs at the Beecher Project in the Black Hills of South Dakota, USA. A comprehensive review of 117 drill holes identified 45 with intercepts greater than 2 metres at 0.20% Rb₂O, demonstrating a high-grade rubidium discovery alongside the project’s established lithium mineral resource.
Notable high-grade rubidium intercepts include 10.5m @ 0.41% Rb₂O from 136.9m in drill hole BDD-23-005, including 5.8m @ 0.50% Rb₂O from 137.9m, and 23.2m @ 0.29% Rb₂O from 80m in drill hole BDD-23-007, including 5.5m @ 0.48% Rb₂O from 95.6m. Other significant intercepts were found in drill holes BDD-23-011 and BDD-23-040. These rubidium intercepts position Beecher among the highest-grade rubidium deposits globally, comparable to other notable deposits in Namibia and Australia.
The addition of high-grade rubidium to the existing JORC lithium resource (2.20 Mt @ 1.05% Li₂O) elevates Beecher to a multi-commodity critical minerals project. IRIS Metals President of U.S. Operations, Matt Hartmann, stated that the discovery reveals world-class rubidium mineralisation grades and positions the company to capture a meaningful share of the Western world’s rubidium supply. The company is strategically expanding their US critical mineral portfolio with the acquisition of the Finley Basin Tungsten Project in Montana, expected to be finalised in the coming weeks.
IRIS Metals is advancing maiden rubidium Mineral Resource Estimates (MRE) for both the Beecher and Tin Mountain projects in Q1-Q2 2026. The updated MRE for Beecher will include all three pegmatites at the project, for both lithium and rubidium. The Beecher Project benefits from an existing mining licence, allowing operations to commence at the company’s discretion, and proximity to excellent infrastructure.
