Color??? Well... Certainly either dark grey or black, but it's tough to be sure. The slides I bought were pretty magenta shifted Ektachromes, so my color balancing may be a bit off. With a highly polished boiler, prepared for her last run, she'll be picking up a lot of green from the trees and blue from the sky, which makes it harder to be sure. I'm pretty sure she was just the normal NP black though. I'm on a calibrated monitor, yours may not exactly match mine. Here's another of the shots I purchased, taken moments later.
Steve