JMDMT #2009 Microfossils of Cyanobacteria in Carbonaceous Meteorites

The James M. DuPont Meteorite Collection - and LEW [3-5]. In the poikilitic area (PA), a large twinned oikocryst of pigeonite (%3E7 mm across) encloses rounded olivine (%3C=1 mm) and euhedral chromite (%3C=100 micron). The pigeonite oikocryst has irregularly-shaped patches of augite usually along its rim. The oikocryst is continuously zoned (Ca3Mg76Fe21~Ca11Mg66Fe23) and augite patches are also zoned (Ca32Mg52Fe16~Ca37Mg49Fe14) (Fig. 1). It is noted that Y pyroxenes in PA have almost identical chemical compositions to those of ALH and LEW [3,4]. Pyroxene in the non-poikilitic area (NPA) of Y is pigeonite that is more Ca-Fe-rich (Ca7Mg65Fe28~Ca13Mg60Fe27) than that in PA, and augite has not been detected in NPA (Fig. 1). A little more Ca-Fe-rich pigeonite (Ca16Mg58Fe26) observed in LEW [3,4] is rare in Y. The equilibration