This game is different things, at different times, to different people. In order to fully advise someone on how to deal with the issue they are having, you must first determine their play style. From your posts, I am now beginning to think you might find it more to your liking to just give yourself what you need. Use the console which is the "`" or tilde key by default, to enter console mode. Then just type in 'item aluminiumingot 12' without the quotes. This will give you a dozen Aluminium ingots. No need to dig to find anything in this game, when you play in Single Player, you are basically an Admin in your own world. If building is why you are their, do not bother with mining or searching. Just give yourself what you need and build whatever you want. You can even just enter 'gm 1' to enter Creative Mode and use the workbenches to create anything. No need to even find the resources. Plus, you can use F2 to enter fly mode and go underground directly to the dungeons. So, no need to even look for them by mining.
I have attached a list of all the items and objects for you to use. If you need help in the console just type 'item help' or 'object help' without the quotes.