Like others have mentioned, I'm immediately thinking of Fairphone. Definitely going to keep an eye on this and hope it's still on my mind when I'm next in the market. Until then, I'm hoping they'll looking into responsible sourcing of conflict minerals [1] [2], possibly in partnership with Fairphone.
Edit: Hmm, can't find an RSS feed. Anyone know if there's one I can follow somewhere?
[1] https://www.fairphone.com/en/impact/fair-materials-sourcing/
[2] https://www.fairphone.com/en/2017/02/01/fairer-materials-a-l...