Digging For Truth

I have a question - is it explainable
how exactly "growth that's sustainable"
will ever include a mine?
After all, by its very design,
you dig and take stuff out of the earth,
then market it for whatever it's worth.

Eventually, beyond a doubt,
the hole will be completely played out,
and the whole operation will halt.
You can't even say it's the owner's fault,
but people will be out of work,
with no one to blame for being a jerk.

Does this somehow mean we should never dig?
Even though the earth is big,
and minerals in fact abound,
must we leave them underground?
Shall all that's deep be unattainable
just because mining is unsustainable?