The St. Mary's County, Maryland, chondrite

Chemical analysis of a 2.9-gram piece of the St. Mary's County, Maryland, meteorite, which fell in 1919, was performed. The meteorite is a very unequilibrated LL3 chondrite. Plots of CaO and MnO concentrations in olivine from relatively metal-rich and metal-poor chondrules and from silicate fragments in the matrix against fayalite content show mixing of an Fe-rich matrix fraction with one and possibly two chondrule fractions. A binary oxide plot of Cr2O3 versus MnO suggests that chromium increases as does manganese with increasing iron content of pyroxene. Both the Mg-rich fraction and pyroxene in metal-poor chondrules and the matrix show a continuous positive correlation of MnO with ferrosilite. Thus there is no compelling evidence to suggest that metal-rich chondrules and metal-poor chondrules represent two distinct chondrule fractions.