text: The ratio of two isotopes of this element is calibrated using troilite from the Canyon Diablo Meteorite.
full_question: The ratio of two isotopes of this element is calibrated using troilite from the Canyon Diablo Meteorite.This element's namesake cycle begins with assimilative and dissimilative reduction from organic materialuntil it is re-incorporated into organic matter. The removal of this element from fossil fuels can be donewith the Claus process. A column of superheated water is used to extract this element in the (*) Fraschprocess. It is found bonded to lead in the mineral galena. An acid of this element is often naturally formed byweathering pyrite; along with nitric acid, that acid is the principal component of acid rain. For 10 points, name thiselement that is responsible for the smell of brimstone and whose odor is reminiscent of rotten eggs.
first_sentence: The ratio of two isotopes of this element is calibrated using troilite from the Canyon Diablo Meteorite.
raw_answer: sulfur [or S] 