There are two mines in Friends of Mineral Town. There is the Spring Mine and the Lake Mine. The Lake Mine is only accessible in the winter (it's in the middle of the lake, so the lake has to be frozen over). There are many things to find in these, such as ores, gems, jewels, tools, and other things.

The Spring Mine is located right beside the Harvest Goddess Pond. In it you can find jewels, a power berry, ores and a recipe.

Spring Mine

Power Berry-----Floor 100
Goddess Jewels-----Floors 60, 102, 123, 152, 155, 171, 190, 202, and 222
Recipe-----Floor 255
Adamantite-----Floor 10 and below
Copper-----All Floors
Gold-----Level 3 and below
Mystrile-----Floor 5 and below
Mythic Stone-----Floor 60
Orichalc-----Floor 10 and below
Silver-----All Floors
Teleport Stone-----Floor 255 and only after your 3rd year

You can only reach the Lake Mine in the winter. The Lake freezes over and you can reach it. You can find cursed tools in the lake mine. Here's where to find them.

Lake Mine
Cursed Ax-----Floor 49
Cursed Fishing Rod-----Floor 29
Cursed Hammer-----Floor 59
Cursed Hoe-----Floor 39
Cursed Sickle-----Floor 79
Cursed Watering Can-----Floor 69