This Krishna is a depiction of the deity in Udupi Krishna Mutt. The local name for the deity is Kadagolu Krishna, meaning Krishna with a butter churner. And that is what is in his right hand. The rope used to turn the butter churner wraps around his body and ends up in his left hand.
The body of this Vigraha is made of copper (or primarily copper). The ornaments, except the crown, are made of brass. The brass ornaments are layed on the copper base, giving us this Ganga Jamuna vigraha. See the close up below, of his left side and the rough patch over the back of his left hand indicates an area where the rope, made of brass, would have been ‘layed’. Now it is broken, giving us some insight as to how Ganga Jamuna pieces were made.
Among the feature worth noting are the Srivatsa mark on the right side of the chest, his tiger-claws necklace and the Vaishnavite religious mark on his forehead. The presence of religious mark suggests a later period for this Vigraha.
The full set of ornaments contrasts his nakedness. This is quite usual for Krishna when he is shown as a toddler or a young boy. Strangely enough the artist has decided to give him a slight paunch, an adult feature.
Most of the Ganga Jamuna Vigrahas I have come across or either Vaishnavite vigraha or deities (Bhairava, Khandobha and Mardhini) popular in North Karnataka. Though some authors suggest Ganga Jamuna vigraha were made in Tanjore region as well, I have not come across any examples.
This Vigraha is about 13.5 cm in height and was made to slide into a slot in a base and would have had a prabhavali. For a complete example, please see this Udupi Krishna. This Vigraha is from North Karnataka and may be dated to the nineteenth century.
Lack of ritual related wear may be due to the breakage. Some consider it is inauspicious to worship badly worn or damaged Vigrahas. Such vigrahas are normally buried, thrown in running water or melted to recover metal. In this case, thankfully, it was preserved.