Ouch!...sounds like it may have only been plated or possibly something entirely different than stainless. Let it dry and see if the surface grunge brushes off revealing clean metal underneath. If not, then it's likely not stainless steel. My experience with recyclers (aka: junkmen) is that very few hold degrees in metallurgy. Also, there are varying degrees of "stainless - ness". Some are magnetic while others are not. That is an indicator of it's ferrous content and also it's degree of resistance to attack. It may still be usable though. Next, try partially embedding a small piece into some basic concrete mix and letting it sit exposed to the elements for a couple of weeks. Maybe even mist it with some salt water. Other than that, it would probably take some (very expensive) lab work to identify what it really might be and whether or not it will work for you. Good luck.

The green colour is not likely to be from zinc. Zinc plating would dissolve very quickly in hydrochloric acid and you would see a noticeable fizzing.

Most likely a deep green colour is from manganese reacted out of the steel.

Howdy all,

The experiment continues....
Today I went outside to retrieve the mesh. It is in a deep ceramic bowl. When the acid was dumped, I left the bowl outside and it filled with rainwater.

Now the mesh is back to being shiny again, lol. All that nasty black layer has completely disappeared. I didn't do anything to it but remove the acid. No shaking or agitating.

I emptied the water and put the bowl under the roof. Now we will see what the air does to the mesh...