  We measure the degree of linear polarization of comet 46P/Wirtanen during two
months, embracing the perihelion passage in 2018 December with phase angles
ranging from {\alpha}=18.1 to 46.4 deg. The polarimetric response PQ obtained
resembles what was previously found in comet C/1975 V1 (West). This suggests
46P/Wirtanen belongs to a group of comets with high maximum positive
polarization. We conducted BVRI photometry of 46P and found either neutral or
blue colour of its dust which is in good accordance with measurements of C/1975
V1 (West). While aperture-average polarimetry of 46P/Wirtanen reveals a nearly
zero polarization PQ at the lowest phase angle {\alpha} = 18.1 deg,
simultaneous imaging polarimetry suggests that the negative polarization (PQ<0)
arises in a region of within 5000 km of the nucleus, where the negative
polarization could be as strong as PQ=-(1.44 +/- 0.15) percent. This
observation suggests the existence of the circumnucleus halo and that the coma
is populated by at least two types of dust particles. One of those reveals a
low positive polarization at side scattering and high negative polarization
near backscattering. Both polarimetric features are simultaneously produced by
weakly absorbing Mg-rich silicate particles. Another type of dust produces
solely positive polarization that could be attributed to carbonaceous
particles. This composition of 46P/Wirtanen coma appears to be similar with
what was previously found in comet C/1975 V1 (West).
