1) Sodium mineral 2) Trigonal mineral
Found on
https://www.crosswordclues.com/clue/clarkeite
Clarkeite is a uranium oxide mineral of composition (Na,Ca,Pb)2(UO2)2(O,OH)3 or (Na,Ca,Pb)(UO2)O(OH)·0-1H2O. The color of samples varies from dark brown to reddish orange. Clarkeite forms by oxidation and replacement of uraninite late during pegmatite crystallization. Although uraninite-bearing granite pegmatites are common, clarkeite is rare and...
Found on
http://en.wikipedia.org/wiki/Clarkeite
No exact match found.
