The Minewood Core is the functional block of a Miner's Tree, one of the four magic trees introduced by the Twilight Forest mod. This block can be activated or deactivated with a right click. When active (i.e. when the gem embedded in the trunk is green), it will draw in nearby ores (note that "ores" include oreberry-bushes, infused stone blocks and amber-bearing stone if playing with Thaumcraft 3, and sometimes just plain stone blocks) with a radius of approximately two chunks. (verification needed) Whether active or inactive, it gives off light with a level of fourteen, the brightness of a torch.
It can be broken and obtained only by using a silk touch tool which is NOT an axe. If you use an axe, TreeCapitator will be invoked, and the axe's silk touch enchantment will be disregarded.