Conflict minerals

I was wondering if Arduino uses any conflict minerals in their products: Columbite-Tantalite/”Coltan” (the most common source of Tantalum), Wolframite (the primary source of Tungsten), Cassiterite (Tin ore), or
Gold. If any of these minerals are used are there any systems in place to make sure that they are not sourced by means of exploiting others?

What kind of parts would they show up in?
I could see Tantalum in caps; I am only aware of ceramic and aluminum electrolytic caps being used tho.
Perhaps tin in the solderpaste used to make the boards. I've never asked Kester where the tin in tin-lead solder paste is from.

Gold, Tungsten?

The headers on the boards have gold-plated contacts.

I think this is a great question and i would be very interested to pick back up on it after so many years. CT and other rare earth metals are mined is such unethical ways it would be interesting to help find alternative sources IF any are used on Arduinos.

Has there been other threads on this since the original date of this post? (I can not find any myself)