Etymology: Previous versions of the OED give the stress as: unsulˈphureous.
(un-prefix1 1.)
ΘΚΠ
the world > matter > chemistry > elements and compounds > metals > specific elements > sulphur > [adjective] > containing, consisting of, or impregnated with > not
unsulphureous1781
unsulphurated1825
1781 Encycl. Brit. VII. 4932/1 To separate Mercury out of an unsulphureous Ore by Distillation.
This entry has not yet been fully updated (first published 1926; most recently modified version published online June 2019).