Yes, agree - and while managing this, monitor closely for conversion to wet gangrene where the dead and necrotic tissue is a nidus for infection which can progress rapidly.

the color is indicated  for dead tissue you see the morgue

The initial dark colour is due to the stasis of blood in the affected area. Later, tissue necrosis and decay of the dead tissue causes a change in this color.

The black colour depend on the transformation of the muscle's myoglobin content in metamyoglobin. In the dry gangrene the reduction of the blood supply causes a reduction of oxygen so, the (Fe++) myoglobin (red colour) pass in (Fe+++) myoglobin (dark colour). Other necrotic processes may complete the transformation of the dark colour in black colour

Dear Qureshi , as you know skin epidermis has no blood supply and takes oxygen and nutrition from superficial papillary dermal plexus, so in dry gangrene epidermis get dry as no perfusion from dermis, here melanosomes that injected from melanocytes in keratinocytes get dry too which stain epidermis black.

Nacrosis is due to the lack of blood supply to the area this should be monitored as the gangrene can spread