Yes @Stevie_B, what @BkrDzn said, except I think Josh meant to say "isn't suss" rather than "is sus", but the gist is they their depletion rates (what they are mining) is exceeded by all of the light blue stuff (the additions to the Resource), especially the "Exploration/Drilling" column, which is organic growth through drilling their own tenements and expanding their own projects and finding more gold.
For those gold miners who can't manage to find more than they are mining organically, they can add ounces via the last column (M&A, a.k.a. Project Acquisition) which is known as inorganic growth and RMS, to their credit, have added ounces through both methods, i.e. organic AND inorganic growth of Resources.
Disclosure: Held.