For four years Martian perchlorate foiled detection of abundant organics by Curiosity rover. Martian perchlorate also decomposed calcium carbonate into CO2 during mass spectrometry tests by the Phoenix lander. Curiosity rover uses CheMin instrument to detect minerals on Mars but fails to detect carbonates. The temperature in CheMin's sample cells sometimes reaches tens of degrees C. In view of the low atmospheric pressure on Mars, the omnipresent perchlorate and the temperature in the sample cell, is it possible that perchlorate decomposed carbonates into CO2 in the sample cells of the CheMin instrument?
Note 1: Calcium sulfate converts into anhydrite around 170 degrees C on Earth. But laboratory experiments indicate that on Mars with its low atmospheric pressure, calcium sulfate naturally converts into anhydrite below zero degrees C.
Note 2: Perchlorate on Mars: