Going forward, he will remain with the company on an advisory or consultancy basis.
Vidal became president on May 31, 2013, after serving as vice president of exploration in Mexico since January 2011. He played a key role in the first discovery and exploration of Bacanora's lithium assets.
No reason was given for the resignation, although SP Angel wondered in a note whether it was related to Vidal disagreeing with the board's challenge of the 3% gross overriding royalty held by the estate of late founder and former chairman Colin Orr-Ewing.
The bank also wondered why the announcement hadn't been issued on December 1.
"We conclude that all is not well with the board of Bacanora Minerals. We expect Bacanora will look to finance the construction of the Sonora project shortly after publication of the feasibility study," SP Angel said.