I've heard many people talk about using rock dust when talking about organic gardening.
From what I understand rock dust is made from crushed rocks. If they are to be used in an organic garden I assume they are made from real rocks; rocks that took many years to form.
It would seem to me that using rock dust is less sustainable than using something like sustainable timber. I would appreciate if someone could explain whether using rock dust is a sustainable practice or are we using up a irreplaceable resource?