Meteorites come from space where there is no water / humidity. That´s how you should keep your iron meteorites - as dry as possible.
Keep them coated with appropriate coatings in order to prevent rusting
Keep your Muonionalusta meteorite in dry air, e.g. in a dry and sealed container and at a constant temperature.
As you most likely want to display your specimen somehow it is rather difficult to keep it away from humidity, especially when you are living in a humid and cold country. Don´t worry. All Muonionalusta meteorites purchased from us have been stabilized so rust should be a minor problem if treated right. A good coating will do the job.
Before coating your meteorite, make sure that it is absolutely clean, so don´t touch it with bare hands ( fingerprints contain acids). Remove all fats with a lipophilic solvent ( thinner or acetone) and let it dry. If you have problems with rust let it soak in pure alcohol for some hours and let it dry. A hot air gun helps chasing out all liquids from small cracks. Don´t ever use tap water due to chlorine which lateron will cause damage to your meteorite.
Don´t rub your etched Muonionalusta meteorite with paper towells as this will make it dull over time. Just let it dry in the air.
There are many philosophies regarding which coating you should apply to an iron meteorite. Some people use liquified grease. Others use thin oils such as WD 40. I wouln´d recommend that because grease won´t penetrate small cracks and WD 40 etc. don´t form a stable coating required for a long maintenance period. Using transparent paint is a little risky as it is hard to remove when a little rust is coming through.
When a meteorite is stabilized just use an ordinary mineral oil, the cheapest is engine oil, to cover it. Dab it with a soft towell and that´s it. Everyone involved with historic vehicles knows that metal parts covered in oil remain well protected for decades, the same is true for meteorites.