  The time-averaged 30 ks Chandra HETGS observation of the micro-quasar GRS
1915+105 in the low hard state reveals for the first time in this source
neutral K absorption edges from Fe, Si, Mg, & S. Ionized resonance absorption
from H-, and He-like Fe (XXV, XXVI), Ca XX and possibly emission from neutral
Fe Kalpha and ionized Fe XXV (forbidden, or the resonance emission component of
a P-Cygni profile) are also seen. We report the tentative detection of the
first astrophysical signature of XAFS in the photoelectric edge of Si (and
possibly Fe and Mg), attributed to material in grains. The large column
densities measured from the neutral edges reveal anomalous Si and Fe
abundances. Scenarios for which the anomalous abundances can be attributed to
surrounding cold material associated with GRS 1915+105 and/or that the
enrichment may signify either a highly unusual supernova/hypernova, or external
supernova activity local to the binary are discussed. We attribute the ionized
features to a hot disk, disk-wind, or corona environment. These features allow
for constraints on the ionization parameter (log xi > 4.15), temperature (T >
2.4 x 10^6 K), and hydrogen equivalent number density (n > 10^{12} cm^{-3}) for
this region. Variability studies with simultaneous RXTE data show that the
light curve count rate tracks changes in the disk blackbody and the power-law
flux. Spectral changes in the Chandra data also track the behavior of the light
curve, and may point to changes in both the ionizing flux and density of the
absorber. A 3.69 Hz QPO and weak first harmonic is seen in the RXTE data.
