Answer
Elemental sulphur is much more stable and long-lasting there.
Work Step by Step
Elemental sulfur deposits are mined beneath the earth’s surface by the Frasch “hot water”. Elemental sulfur is only found on the earth’s surface near volcanoes and hot springs, where the water brings up H$_{2}$S which oxidizes to elemental sulfur by special anaerobic bacteria. In time, at the earth’s surface, the sulfur will continue to oxidize, with the help of aerobic bacteria, to thiosulfate $(S_{2}O _{3} ^{2-})$, tetrathionate $(S_4O_{6}^{2-} )$ and sulfate $(SO_4^{2-} )$ ions. The aerobic bacteria need oxygen to survive and therefore have far lower populations beneath the earth’s surface, so the elemental sulfur is much more stable and long-lasting there.
