and people saying mines are hard to find? really? are you playing old or outdated seeds or what is this? in each bigger mistland biome youll find more than enough of these. and they are nearly always easy to spot due to the blue lights which marrk them very often.

It is completely random. I have one swath of mistland that has exactly 1 mine in it over a giant area. I have another with 4 on top of each other. But the only way to know which is which without cheating is to go there and do a grid pattern (because you can't see) making noise to see if you can attract a large group of seekers (the easiest indication of a mine is finding 3+ seekers at once). Note that about 1/2 of the mines in my seed are without blue lights, and about 75% of towers WITH blue lights are not mines but outposts. You are going down the stairs etc at the unpopulated outpost towers, right? Those can have mines, but more often than not, they don't, but it takes time to get there and check it out once you spot it.

And many mines have low cores only. Then it seems like there is a gap in the distribution, there are a bunch of 0-3 core mines and some 5+ mines. The 5+ are not rare, but they are also not common, at a rough guess its 2 or 3 bad ones to every 5+ but I only have a dozen or so data points.

It could be expectations too. Generate any seed with the online map thing and look at them. There are 3-4 crypts in the forest for every 1 mine in the ML by same area size, and if you miss one, its a big miss. Maybe people expected a higher density. Maybe they expected more cores per mine. Or a combo of all of it. At the end of the day though RNG is RNG and some people are getting frustrated by their luck, while others are celebrating.

its also nothing new, see the 1000s of 'wheres da swamp crypts' for folks with bad swamp areas.