  We present infrared spectroscopy of the classical nova V339 Delphini,
obtained over a $\sim2$ year period. The infrared emission lines were initially
symmetrical, with HWHM velocities of 525 km s$^{-1}$. In later
($t\gtrsim77$days, where $t$ is the time from outburst) spectra however, the
lines displayed a distinct asymmetry, with a much stronger blue wing, possibly
due to obscuration of the receding component by dust. Dust formation commenced
at $\sim$ day 34.75 at a condensation temperature of $1480\pm20$K, consistent
with graphitic carbon. Thereafter the dust temperature declined with time as
$T_{\rm d}\propto{t}^{-0.346}$, also consistent with graphitic carbon. The mass
of dust initally rose, as a result of an increase in grain size and/or number,
peaked at $\sim$ day 100, and then declined precipitously. This decline was
most likely caused by grain shattering due to electrostatic stress after the
dust was exposed to X-radiation. An Appendix summarises Planck Means for
carbon, and the determination of grain mass and radius for a carbon dust shell.
