Berkeley Energia (ASX:BKY) has reported a maiden mineral resource estimate (MRE) of 11.8 million tonnes at 0.41% lithium oxide and 0.21% rubidium oxide for its Conchas Project in Spain.
The inferred resource contains approximately 49,000 tonnes of lithium oxide (Li2O) and 25,200 tonnes of rubidium oxide (Rb2O). Mineralisation began at the surface and remained open at depth.
“This initial MRE is a significant milestone for the company’s Critical Minerals Exploration Initiative in Spain and clearly demonstrates the significant potential of the Conchas Project,” Executive Director Robert Behets says.
The resource also contains accessory tin, caesium, beryllium, niobium, and tantalum hosted within a muscovitic leucogranite unit.
Berkeley says the deposit is amenable to bulk-tonnage, open-pit mining based on the shallow, thick zones of mineralisation.
The MRE was prepared by independent consultants Maja Mining and reported in accordance with JORC Code 2012.
BKY used a net smelter return cut-off of US$100 ($142.7) per tonne, above the calculated breakeven of US$18 per tonne, to provide a conservative basis for the resource.
Preliminary metallurgical testing achieved 77.5% overall lithium recovery @ 2.23% Li2O grade and 62.7% overall rubidium recovery @ 0.87% Rb2O grade through cleaner flotation.
A European critical minerals resource takes shape
The Conchas Investigation Permit covers 31km2 in Salamanca province, approximately 21km from Ciudad Rodrigo and 110km from Salamanca city.
Conchas sits within the Central Iberian Zone, known for lithium mineralisation associated with highly fractionated granitic intrusions.
Berkeley completed two drilling campaigns totalling 38 holes for 2,369m. These include five reverse circulation (RC) holes in 2022 and 33 RC holes plus three diamond holes in 2024.
The company also conducted electrical resistivity tomography surveys and density determinations to support the resource estimate.
Rubidium is classified as a critical mineral by the US, Japan, and New Zealand due to its strategic importance in defence, aerospace, communications, and renewable energy applications.
The EU designates lithium as a critical and strategic material for decarbonisation and energy security.
Behets says the company will continue advancing the project with additional infill drilling to increase resource classification and a second phase of metallurgical testwork to optimise processing methods.
Berkeley Energia is a Spanish-focused critical minerals developer advancing the Conchas Lithium-Rubidium Project and the Salamanca Uranium Project.
Write to JC Villarba at Mining.com.au
Images: Berkeley Energia
