Track lighting connectors - brass? Aluminum? Tinned copper?
This is exactly what I was trying to say before, (what you found on Nora's spec sheet) admittedly not as clearly as I should. These manufacturers are not going to put their products at risk with such a fundamental flaw.  I have seen bus work in load centers over the years and learned that all those different colors mean little of nothing.  People will often think that just because a contact metal is silver in color, it has to be aluminum.  These manufacturers know very well the dangers of oxidation and specifically the problems with the oxidation of aluminum.  They avoid it like the plague.  Additionally, they know the results of mixing dissimilar base metals and the electrolysis that if can cause. This, they avoid as well.  The problem gets worse:  The metal ‘copper’ alone or in high concentration is actually a problem also because although it is an excellent conductor it alone is too soft to stand up to the rigors of an electrical contact surface.  Therefore, manufacturers combing copper with other alloys to make it stronger. Every manufacturer has their own proprietary mix and the resulting look or color is different in every case.  They pay metallurgist big money to figure these things out. You can be quite sure of this; the contact metal, you speak of, will stand up the rigors required and at the same time do an efficient job of conducting the electricity necessary without harmful reactions between metals. I hope I made this more clear. P.