Thanks to one of MB's users (who wants to remain anonymous yet gave consent for sharing), I stumbled upon the following icons:https://github.com/Keyamoon/IcoMoon-Free/tree/master/PNG/16px
Very elegant and beautiful.
I'm using CalciumMETRO as a skin, and all other icons I could find (here on the forum or elsewhere) looked very 'fat' and black. Maybe someone else will enjoy these too...
(PS: I downloaded the 64px versions - apparently no problem for MB, just shows them smaller.)