I was surprised to find another city with the -gorsk ending: Железногoрск (Zheleznogorsk), formerly known as Krasnoyarsk-26.
It sounded familiar, and I immediately looked up Iron (the metal), which is Железо. Notice there is no "н".
So why does it inflect this way when a city gets named after a metal? Are there special rules for naming cities like this?
BTW I also looked up "Железно" on Google Translate, and it said it means "irons". This only confused me even more.