If you have an iron metoerite, it's a good idea to show it a bit of attention from time to time. Iron is iron, and even the more stable meteorites can show a little rust over time. Yesterday I spent a while scrubbing and oiling some of my Sikhote-Alin material.
I have an old nail brush for times like this - it's pretty good for getting rid of the loose, oxidised flakes on the surface of the meteorite. I gave each lump a decent going over with the brush before rubbing them with a rag soaked with transmission fluid. You can use pretty much any oil. Once I'd done that, I wiped them with kitchen roll to get rid of most of the oil and leave a light sheen.
You can give them a deeper clean if you think it necessary. Half-fill a small bowl with water before adding a few heaped spoonfuls of baking powder and dumping in the meteorites. Leave them to fizz for about half an hour before taking them out and fully drying them off. Next, you soak them in oil for a few minutes before removing and wiping mostly dry with kitchen roll. Be careful how you dispose of the oil, too.