Four armed Ganesha is sitting on a mouse (See the rear view), his vahana. The mouse, in turn, is supported by a hemispherical base with a rim.
The finish, decoration and the proportion of different elements gives a folkish feel to this idol. There are remnants of red pigments used in worship. The idol itself does not show any wear related to ritual use.
The five-leafed pierced protrusion as crown and the hemispherical base this idol may be from Orissa/Bengal region.
The idol is about 14 cm in height. The dealer estimated it dates to the eighteenth century. The patina is dark but uneven. But I am good with the estimated age.