  We report observations of color in the inner coma of Comet C/2013 UQ4
(Catalina) with the broadband B and R filters. We find significant temporal
variations of the color slope, ranging from -12.67 $\pm$ 8.16 \% per 0.1~$\mu$m
up to $35.09 \pm 11.7$ \% per 0.1~$\mu$m.It is significant that the comet
changes color from red to blue over only a two-day period. Such dispersion
cannot be characterized with an average color slope. We also observe Comet
C/2013 UQ4 (Catalina) in infrared using Spitzer and find no significant
CO/CO$_{2}$ gaseous species in its coma. Therefore, we classify Comet C/2013
UQ4 (Catalina) as a dust-rich comet and attribute the measured color slope to
its dust. We analyze the color slope using the model of agglomerated debris
particles and conclude that the C/2013 UQ4 coma was chemically heterogeneous,
consisting of at least two components. The first component producing the bluest
color is consistent with Mg-rich silicates. There are three different options
for the second component producing the reddest color. This color is consistent
with either Mg-Fe silicates, kerogen type II, or organic matter processed with
a low dose of UV radiation.
