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The St. Mary's County, Maryland, Chondrite
Albert F. Noonan, Eugene Jarosewich, and Roy S. Clarke, Jr.
ABSTRACT
The St. Mary's County, Maryland, meteorite fell
on an afternoon in June of 1919. One individual
stone of perhaps 500 grams is known to have been
recovered, but only a 23.4 gram fragment was
preserved. A 2.9 gram piece was made available
for laboratory investigations.
Chemical parameters determined from the bulk
chemical analysis, compositions of the major silicates,
and the overall texture of the meteorite
show it to be an LL3_chondrite. The average
compositions of oliyine, Fa 14.4 (Fa, 0.2-76.6), and
low-Ca pyroxene, Fs 9.9 (Fs, 0.5-37.5), with %MD's
of 51.9 and 67.3, respectively, show that this meteorite
is among the least equilibrated of the ordinary
chondrites. Calcium and manganese concentrations
in olivine plotted against fayalite content show
mixing of an Fe-rich matrix fraction with one and
possibly two chondrule fractions. Oxide plots of
minor elements in low-Ca pyroxene (