The missions generally ask you to search for Carbonic, Ferric, or Silicate. Sometimes they will ask you to search for Ishik or VanAzek. VanAzek is generally agreed to be the biggest pain because it is generally spread out over a wide area. There are a handful of missions to find Xithricite.
These missions are generally thought to be very boring, so don't expect excitement or glory. But the reward, the advanced mineral scanner, can significantly speed up searching for rare ores. ===Trade Guild Mineral Missions=== The Trade Guild offers, among many other mission types, "mineral" missions. Mineral Missions are most abundent at mining stations. They are offered elsewhere but not at the same volume you can get at a mining specific station. Most of the time these missoins are oriented around getting the station that you've accepted the mission from the ores that is most needed. A majority of the time the station will ask for either aqueaus or silicate ore to be collected. If you spend a while doing these missions you will get other types ranging from Ferric, Carbonic, VanAzek, and Ishik. On very rare occasions though, they may ask for you to bring them back some Pentric, Xithricite, or Pyronic ore. I have yet to take a mission that has asked for the more extremely rare ores, though it's certainly possible. The pay for these missions vary but for the majority they are around 1000cr a mission and around 800-1400 trade xp. The mining xp you get for mining the ores is negligable but on a massive scale can get you the lower levels fairly quick. I've also found that the mining missions are a great way to build faction standing with a particular faction. Search out a specific faction and see if they also have a mining station.
===Profitability===