I PROPOSE TO EXPERIMENTALLY MEASURE THE EFFECT OF LOW OXYGEN FUGACITY (FO2) ON THE VOLATILE CONTENT (H C S F CL) OF NOMINALLY VOLATILE-FREE MINERALS (NVM): OLIVINE PYROXENE AND FELDSPAR. VOLATILE PARTITIONING HAS BEEN INVESTIGATED IN TERRESTRIAL SILICATES UNDER OXIDIZING CONDITIONS HOWEVER THIS WOULD BE THE FIRST STUDY AT THESE HIGHLY REDUCING CONDITIONS (IW-3 TO IW-7). THERE IS A GROWING RECOGNITION THAT SUCH LOW FO2 CONDITION WERE WIDESPREAD AND IMPORTANT IN THE FORMATION OF PLANETARY BODIES INCLUDING ENSTATITE CHONDRITES AUBRITES MERCURY AND POSSIBLY EVEN EARLY EARTH. REDUCING CONDITIONS HAVE BEEN SHOWN TO AFFECT ALL ASPECTS OF THE CHEMICAL AND PHYSICAL PROPERTIES OF MINERALS AND MELTS AS OXYGEN IS THE DOMINANT NEGATIVELY CHARGED ELEMENT AND IS INVOLVED IN NEARLY ALL REACTIONS. CONTROLLED EXPERIMENTS WILL DETERMINE THE EFFECT OF FO2 AND PRESSURE ON VOLATILE CONTENT OF SILICATES. A SUITE OF REDUCED METEORITES INCLUDING EH EL AND AUBRITES WILL BE ANALYZED TO TEST THE PRODUCED RELATIONSHIP BETWEEN OXYGEN FUGACITY AND SILICATE VOLATILE CONTENT. EXPERIMENTS WILL BE RUN FROM 0.1 GPA IN AN INTERNALLY-HEATED PRESSURE VESSEL TO 1 AND 2 GPA IN THE PISTON CYLINDER FOR A RANGE OF FO2 (IW-3 TO IW-7). THE ELECTRON MICROPROBE (EPMA) WILL BE USED TO ANALYZE MAJOR AND MINOR ELEMENTS INCLUDING S NA AND K AND THE SECONDARY ION MASS SPECTROMETER (SIMS) WILL BE USED TO ANALYZE TRACE VOLATILES (H C S CL F). APPLICATIONS INCLUDE 1) ESTIMATING THE FO2 OF SAMPLES FROM VOLATILE CONTENT OF NVM AND 2) ESTIMATING VOLATILE CONTENT OF REDUCED PLANETARY INTERIORS. PLACING THERMODYNAMIC CONSTRAINTS ON VOLATILES IN NVM IN THESE REDUCED SYSTEMS IS CRUCIAL BECAUSE THEY HAVE AN OUTSIZED EFFECT ON MINERAL PROPERTIES SUCH AS STIFFNESS VISCOSITY ONSET OF MELTING AS WELL AS EXPLOSIVE VOLCANISM ON MERCURY