By Fabio Teixeira

RIO DE JANEIRO Sigma Lithium Chief Operating Officer Brian Talbot left the company at the end of last month, he told Reuters on Thursday, in the latest management shakeup at the Vancouver-based miner.

Talbot became COO last year, overseeing operations at Sigma's flagship Grota do Cirilo mine. His exit from Sigma, the poster child for Brazil's budding lithium sector, comes amid a legal battle between the husband-and-wife pair who ran the company together until earlier this year.

Talbot said he presented his resignation to Sigma in late July and his last day at the company was Friday, Sept. 29. He did not give a reason for his exit.

Sigma did not immediately reply to a request for comment.

Last week, Reuters reported that divorce proceedings between current Sigma Chief Executive Ana Cabral-Gardner and Calvyn Gardner, her husband and former co-CEO, had triggered several lawsuits, including a dispute over some of the mineral rights where Sigma plans to build mining pits.

At the time, Sigma told Reuters the dispute would not affect its expansion plans, as it said it can develop the area via a "waste sharing agreement." It also said that efforts to attract a buyer for Sigma, which is looking for a buyout, were not affected.

Gardner left his co-CEO role in January, and Sigma announced a new chief financial officer in August.

(Reporting by Fabio Teixeira; Editing by Gabriel Stargardter and Brad Haynes; Editing by Susan Fenton)