I got my wound debrided on monday, silversorb has been applied to aid in moist wound healing, since tues, theres a black spot over the skin near wound?

Hard to say. A black spot could mean the skin is dead in that area and there could be some type of infection there. However, it could be a spot where a little blob of silver oxidized and wouldn't be serious. You might be able to tell more by very gently trying to wash the area. If it comes right off, and the skin looks normal underneath, no worries.
Normal . Hello, this is a normal occurrence. Since the substance used contains silver, the skin has been temporarily tattooed by the silver, but it will eventually fade and dissapear.
Silver staining skin. Most likely the silver leaked out on to the skin turning it a different color but always best to be safe and have it checked out by your doctor.