Abstract: An apparatus (10) for identifying molecular contamination in an environment includes a pair of crystals (12, 14) supported within supports (16, 18, 20) which are cantilevered to a base (44) by standoffs (36). Base is housed within an enclosure (56) which opens through an opening (54) to an environment to be tested. Contaminants from the environment are deposited on sensing crystal (12) which, after a build up of the contaminants thereon, is heated by a heater. Through a thermo-gravimetric analysis, the points at which contaminants on crystal (12) sublime provide a means for identifying the contaminants.