It has acquired a new exploration licence for an area that covers four old mines, including the historic Martanberg copper mine that was in operation either side of the turn of the 19th century.
The Martanberg field is known for its copper-rich skarn-style mineralization, Sienna said.
The underground workings extended to depths of 80 to 100 metres, and little to no modern exploration has been conducted in the area; Sienna plans to bring modern techniques and views to this added acreage.
The Slattberg cobalt-nickel-copper project now consists of three exploration licences covering 12,733 acres and at least 16 historic mines.
READ Sienna Resources says initial magnetic survey work defines additional drill targets at Slattberg cobalt-nickel-copper project
The announcement of increased land holdings follows hot on the heels of last month’s announcement concerning the continuing magnetic survey work on the Slattberg cobalt-nickel-copper project in Sweden
"We are very pleased to significantly expand our Swedish landholdings,” said Jason Gigliotti, the president of Sienna Resources.
“We are in a strong cash position right now and with the new data obtained from the magnetic survey recently completed, we are ready to commence drilling shortly. Cobalt prices are currently at fresh 10-year highs right now and show no signs of slowing as the global demand on the battery metals continues to strengthen. We look forward to a very active 2018," Gigliotti said.
Shares in Sienna rose 1.7% to C$0.305 following the announcement.