Greenland isn't entirely covered in ice. Take a look at any of the mineral resources maps floating around for the country. Everything's on the coastal margins in places only covered by seasonal snow. The interior is a big blank because no one's been able to search under the ice.

However, the adjacent Canadian provinces (Nunavut & Northern Labrador) share many of the same geologic provinces, also without significant glaciation. There aren't a lot of big mines up there relative to the mineral wealth because it's simply too challenging. Constructing big infrastructure in the arctic takes resources approaching nation-state levels. Most mining companies can't muster that or maintain it long-term.