Wiktionary
stillwaterite
n. (context mineralogy English) A trigonal-rhombohedral gray mineral containing arsenic and palladium.
Wikipedia
Stillwaterite
The palladium arsenide mineral Stillwaterite has a general formula of PdAs. Stillwaterite was first discovered in the Banded and Upper zones of the Stillwater igneous complex in Montana, US, and has been reported in the Lac-des-Iles area of Ontario, Canada. Outside of North America, this rare mineral has been found in northern Finland.