Global Lithium Resources (ASX:GL1) said a definitive feasibility study confirmed the Manna Lithium project as a long-life and economically robust lithium asset, according to a Thursday filing with the Australian bourse.

The study generated an internal rate of return post-tax of about 26%, and a total mineral resource estimate of 51.6 million tonnes at 1% lithium oxide (Li2O3), the filing said.

It also showed an initial life of mine of 14.3 years, with an all-in-sustaining cost of $738 per tonne and over 82% of the mining inventory supported by ore reserves, the filing added.

Shares of the company fell 3% in recent Thursday trade.