  SF$_{6}$ is an inert and electronegative gas that has a long history of use
in high voltage insulation and numerous other industrial applications. Although
SF$_{6}$ is used as a trace component to introduce stability in tracking
chambers, its highly electronegative properties have limited its use in
tracking detectors. In this work we present a series of measurements with
SF$_{6}$ as the primary gas in a low pressure Time Projection Chamber (TPC),
with a thick GEM used as the avalanche and readout device. The first results of
an $^{55}$Fe energy spectrum in SF$_{6}$ are presented. Measurements of the
mobility and longitudinal diffusion confirm the negative ion drift of SF$_{6}$.
However, the observed waveforms have a peculiar but interesting structure that
indicates multiple drift species and a dependence on the reduced field ($E/p$),
as well as on the level of water vapor contamination. The discovery of a
distinct secondary peak in the waveform, together with its identification and
use for fiducializing events in the TPC, are also presented. Our measurements
demonstrate that SF$_{6}$ is an ideal gas for directional dark matter
detection. In particular, the high fluorine content is desirable for
spin-dependent sensitivity, negative ion drift ensures low diffusion over large
drift distances, and the multiple species of charge carriers allow for full
detector fiducialization.
