Abstract

Fractal and two-point radial autocorrelation analysis has been performed on 16 images of experimental products and 44 images of natural graphic K-feldspar-quartz textures from several pegmatite localities. The box-counting fractal dimension and the lacunarity of experimental and many natural images overlap, although natural samples from one of the pegmatites extend to lower values of the fractal dimension and higher values of lacunarity than seen in experiments. The normalized distance between quartz crystals measured by autocorrelation analysis in experimental (11 samples) and natural (26 samples) graphic textures is similar, although experiments display greater variation. The similarity of the results from experimental and natural samples demonstrates that the conditions of graphic texture formation in laboratory experiments at length scales on the order of microns can be extrapolated to natural length-scales on the order of centimeters to meters. The image analysis of orthogonal slices suggests significant effects of the crystallographic orientation of the graphic intergrowth. The three measures used in this study can be applied to other graphic granite textures if the orientation effects are taken into account and may provide a quantitative classification system that leads to a better understanding of their formation.

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