Local purities of crystal faces of m-chloronitrobenzene (m-CNB) growing from its binary melts containing p-chloronitrobenzene (p-CNB) were measured and were correlated with the local linear growth rates. The local purity is determined from composition of the part of the crystal related to the growth of a certain crystal face. As the result of the experiments, the growth rates in the directions of y-axis and + z-axis are controlled by the presence of p-CNB, and p-CNB was detected in most crystal faces at a variety of levels depending on the crystallographic faces. The existence of the noncrystallizing component (p-CNB) in the crystal was attributed to the inclusion of mother liquor during the growth of crystals. The fractional amounts of inclusions, calculated from the local concentration of p-CNB, were defined as the inclusion factors of each crystal face and were correlated with the local linear growth rates. From the experimental results of local purity, it was found that the faster the crystal face grows the more the purity of m-CNB decreases. With the crystal structure of m-CNB to analyze the molecular arrangements, each face has different characteristic functional group. The linear growth rates of (0 2 0) and rounded faces which have the same functional group were slower than (0 2 1) face. (C) 2002 Elsevier Science B.V. AII rights reserved.