Akkadian

burallu - (a stone) (CAD B 326, AHw 139)

A loanword from Iranian, cf. Parthian bylwr “rock crystal” (Henning 1937, 81), Middle Persian bēlūr ‘crystal’ (Pahlavi 18) and see further Ciancaglini 2008, 128 f. and Beekes 212 where an eventual Indo-Aryan (and, ultimately, Dravidian) etymology is discussed.