In this Letter we report a unique fractal aggregation behavior of NH4C
l crystallites grown in agarose gel. The fractal branches consist of f
aceted crystallites with remarkable correlations in their crystallogra
phic orientations, which are formed by successive heterogeneous nuclea
tions. Unlike the conventional fractal growth, this aggregation proces
s occurs at a low growth driving force with strong crystallographic an
isotropy, which leads to the ordering in the fractal branches.