Apart from some rare earth metals in the southwest corner of occupied Donesk where it borders eastern Zaporizhzhia - so around Mariupol. Otherwise, there isn't actually that much else in occupied areas to get excited about.
Russia, with China, is focusing on the most lucrative deposits in this area.
There were actually far bigger, but less exotic, deposits across Dniprovsko-Donetska and Voronezhska - areas which have been fully reclaimed by Ukraine.
Everything else of mineral worth is in Ukrainian territory Russia has thus far failed to set boots in. That includes the Ukrainian held northern half of Zaporizhzhia oblast, the population of which dwarfs the farmland and small towns in the occupied south. (A true referendum of that oblast would've had the vatnik seccessionists outvoted three to one, and would've killed the lie that ethnic Russians who speak Russian all wanted Russian annexation - over half of that population is Russian speaking and ethnic Russians who fled the occupation.)
If President Trump really does think he can do a deal that includes rare earth deposits, he must be angling for Zaporizhzia Oblast and even part of to be returned to Ukraine. Otherwise, his numbers don't add up.

A nice graphic from Lyellcollection.org, a British geological site. One wonders if it jives with what the Zelensky administration is offering / negotiating with President Trump, if indeed this is going further.
Thanks for splendid reply. Judge Napolitano and his regular guests on Judging Freedom )(e.g. Col Douglas MacGregor, Larry Johnsaon, Ray McGovern) hhave all convinced themsa4elves that Russian troops are sitting on ALL the rarew earths extant in Ukrainke. You cleared that up splendidly.