I haz suggestion to turn silverfish into replicators, it takes 3 of them to destroy one block of stone or ore, and when they destroy one, there is a new silverfish of that type, if its stone its a normal one, if its iron its an orange one and slightly stronger. If its gold its yellow and has low health but high damage. If its diamond its really powerful.
Iron ones take 5 to destroy
Gold take 6
Diamond take 8
This is only when they are idle, when you arent attracting their attention.
and it also isnt instant, it takes time for them to replicate and mine the block out