Unfortunately, as you've said, M&C don't seem to be listed in all the usual places, otherwise you could possibly establish what it was. At only 3g (incredibly light) it must be very small, so would not have been a dipping pen. I would be tempted to ho;d on to it, even with silver prices being quite high, at 1/10 oz the scrap value for this little item would be very little, so I would hold on to it and treat it as a curio.
