That I find it unrealistic and immersion breaking for me?
The look of them are unrealistic, but surface ores are common in reality... just highly unlikely to make formations.
I don't really see how this breaks immersion so greatly. That word is getting thrown around in the gaming community too much. Nobody was like, oh wow, I was so completely involved with this game, I completely forgot about my reality, but it all came to an abrupt end the moment I saw a mineral deposit. Really? It has its purpose that fits into the game and doesn't disrupt anything. It's not like it's a spinning disco ball with shimmering particles flying off it. But we'll come back to immersion.
Anyway, not so much that, but this: "its easy to think an above ground coal deposit is another player especially at night time". Under that logic, several things would have to get removed from the game because they might resemble players to some people in a pvp game. Since when is that grounds to make a change? If I was a dev of this game and heard that statement, I would put in more things that look like players just to give everybody a hard time.
Then, you tried going the whole "mining is brainless" route. OK, fine, I can get on board with that. But then you presented this metal detector with more abilities than we have now (the type of ore and the depth of ore), making it equally as brainless as the nodes... not to mention even more immersion-breaking. Sure, metal detectors exist... but not at that kind of level unless its an industrial giant and certainly not with the technical know-how of your character in the first week of the game. I don't want to build one of those things before the first horde. I play solo, high numbers, high difficulty... I need resources yesterday.