Discovery of a New Chromium Sulfide Mineral, Cr_5S_6 in Murchison

During a nano-mineralogy investigation of the Murchison CM2 meteorite, a new chromium sulfide mineral, Cr_5S_6, was identified as inclusions in two isolated olivine grains. High-resolution SEM, electron-backscatter diffraction (EBSD) and electron microprobe analyses have been used to characterize its composition and structure. The phase is known from laboratory studies of the Cr-S system [1] but has not been previously reported in nature. The new mineral has been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA 2010-003).