Pioneer Lithium (ASX:PLN) said rock chip samples from the Skull Creek uranium project in Colorado returned up to 1,240 parts per million of triuranium octoxide, confirming the potential for large-scale mineralization, according to a Monday filing with the Australian bourse.

The samples were taken at the surface over the Sego Sandstone and Carbonaceous Shale units at the Blue Mountain and Railroad prospects within the project. The mining company said the sample results indicate the presence of economic grades of uranium mineralization at depth, per the filing.

Pioneer Lithium's shares rose 10% in recent trade.