Bm mandolin chord
B minor on mandolin is 4-0-2-2, low string to high (G D A E), and it sounds B D B F#. It is one of the minor chords on the chart.
The shape
Nut at the top, strings running down the page low to high, G D A E. The numbers under the name are the frets in that order. A filled dot is a finger and a hollow dot is the string you add when your hand allows it. An o above the nut is an open string, and a dashed o is an open string you can leave out.
Third finger on the G pair at the fourth fret, first finger on the A pair at the second, second finger on the E pair at the second, and the D pair rings open in the middle.
That open D is the minor third, which is why this shape works as well as it does: the note that makes it minor is one you never have to fret. The B on the bottom is the root, and there is a second B an octave above it on the A pair.
Where it turns up
The relative minor of D, which makes it the vi chord in that key, and the ii chord in A.
Tunes that use it
Written out here with the chord letters over the bars where the change happens, so you can put the shape under something rather than drilling it on its own.
A diagram cannot hear you
Mandolin Trainer listens through your microphone, hears which notes of the chord are sounding, and names the string that should be carrying a note it cannot hear, which is the thing a diagram can never do. The Chord Theory section teaches these shapes and then checks them. Free while it is in beta.
Open the appRuns in your browser. The audio never leaves your device. iOS app coming soon.
Other minor chords
Low shapes for the five minors that turn up most. Every one of them is a major with its third dropped a fret and nothing else touched.