hey, anybody knows which ores should be kept ? I have a ton in my etc and I don't want to drop useful ones..
Mithril and Steel are probably the most sought after regular ores. Among crystal ores I would say Power and Dex. Occasionally the dark crystal ores are sought after, but they're so abundant that they're basically not worth anything. Anything else I would probably keep some as back up, but you could probably npc the rest.
Adding to that, silver and emerald are relatively rare compared to others ores (i.e., not dropped from monsters that are in popular maps), but they are not in demand either.