  We analyze the dust environment of the distant comet C/2014 A4 (SONEAR), with
a perihelion distance near 4.1~au, using comprehensive observations obtained by
different methods. We present an analysis of spectroscopy, photometry, and
polarimetry of comet C/2014 A4 (SONEAR), which were performed on November
5~--~7, 2015, when its heliocentric distance was 4.2~au and phase angle was
4.7$^\circ$. Long-slit spectra and photometric and linear polarimetric images
were obtained using the focal reducer SCORPIO-2 attached to the prime focus of
the 6-m telescope BTA (SAO RAS, Russia). We simulated the behavior of color and
polarization in the coma presenting the cometary dust as a set of polydisperse
polyshapes rough spheroids. No emissions were detected in the
3800~--~7200~$\AA$ wavelength range. The continuum showed a reddening effect
with the normalized gradient of reflectivity 21.6$\pm$0.2\% per 1000~$\AA$
within the 4650~--~6200~$\AA$ wavelength region. The fan-like structure in the
sunward hemisphere was detected. The radial profiles of surface brightness
differ for r-sdss and g-sdss filters, indicating predominance of submicron and
micron-sized particles in cometary coma. The dust color (g--r) varies from
0.75$ \pm $0.05$^m$ to 0.45$ \pm $0.06$^m$ along the tail. For aperture radius
near 20~000~km, the dust productions in various filters were estimated as
$Af\rho $~=~680$\pm$18~cm (r-sdss) and 887$ \pm $16~cm (g-sdss). The
polarization map showed spatial variations of polarization over the coma from
about --3\% near the nucleus to --8\% at cometocentric distance about
150~000~km. Our simulations show that the dust particles were dominated (or
covered) by ice and tholin-like organics. Spatial changes in the color and
polarization can be explained by particle fragmentation.
