For the most part, you’re only going to be finding argon crystals in the void, and they spawn/drop in any of the Void missions however for this you’re going to be wanting to do the capture missions, doesn’t matter which capture mission you pick though so you can pick whichever one you like.
I also recommend having a loot detector on whatever frame you’re running for this mission.
Once you capture the target all your going to be doing is searching the entire map opening and breaking every crate/container you can find as argon crystals can drop from them.
