Thoughts on strategic metals as a diversification play?

I've been heavy on gold and uranium for a while, but I'm curious if anyone is looking at the niche side of things. These markets are usually tiny and hard for retail to touch, but they seem to have very low correlation with the rest of the market. Does a fixed basket of these metals make sense as a long-term hold, or is it too obscure? I'm trying to figure out if the supply constraints are as tight as the macro reports suggest.