the.com/brimstone

means An old name for sulfur, the pale yellow mineral that burns with a choking blue flame and a stink like rotten eggs — forever linked with fire-and-brimstone visions of hell.

from From Old English brynstān — brin (burning) plus stān (stone), literally 'burning stone.' Sulfur deposits near volcanic vents really do ignite and smolder, so the name was first just plain description. Its starring role in hellfire sermons came later, when preachers borrowed the smell of the actual mineral to make damnation feel chemically real.