|The following is based on Fallout 3 cut content and has not been confirmed by canon sources.|
The mine itself seems to be a combination of nails, an empty jar, a stick of dynamite and a lit cigarette. The cigarette burns down, and eventually ignites the fuse on the dynamite. When it explodes, it sends the nails flying, due to where the dynamite is placed, it would send the nails in a limited direction. Also this wouldn't be able to function as a mine, due to the fact that cigarettes are not proximity activated. It would instead function like a time bomb.
The Mason jar mine was set to appear in Fallout 3, but was cut before release.