Mid-infrared (MIR) spectroscopy has been used with great success to
quantitatively determine the mineralogy of geologic samples. It has been
employed in a variety of contexts from determining bulk composition of
powdered samples to spectroscopic imaging of rock thin sections via
micro-FTIR. Recent advances allow for IR measurements at the nanoscale.
Near field nanoscale infrared imaging and spectroscopy with a broadband
source (nano-FTIR) enable understanding of the spatial relationships
between compositionally distinct materials within a sample. This will be
of particular use when analyzing returned samples from Bennu and Ryugu,
which are thought to be compositionally like CI or CM2 carbonaceous
chondrites. Returned samples will likely contain olivine/pyroxene
chondrules that have been transformed into hydrous phyllosilicates,
sulfides, carbonates, and other alteration phases. The use of near-field
infrared techniques to probe the boundaries between once pristine
chondrules and alteration phases at the nanoscale is a novel approach to
furthering our understanding of the compositional evolution of
carbonaceous asteroids and the processes that drive their evolution.
Here we report the results of nano-FTIR spectroscopy and imaging
measurements performed on the carbonaceous chondrite Allan Hills (ALH)
83100 (CM1/2). We show with nanoscale resolution that spatially resolved
Fe-Mg variations exist within the phylosilicates around a chondrule rim.
We also present effects of crystal orientation on the nano-FTIR spectra
to account for the spectral differences between the meteorite and