Sulfur
From London's Ghost Acres
The element's largest commercial use (after mostly being converted to sulfuric acid) is to produce sulfate and phosphate fertilizers, because of the relatively high requirement of plants for sulfur and phosphorus. Sulfuric acid is also a primary industrial chemical outside fertilizer manufacture. Other uses for the element are in matches, insecticides and fungicides. It is also used in the vulcanization of rubber.
https://en.wikipedia.org/wiki/Sulfur