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A. Photomicrograph of two crystals of plagioclase feldspar joined along a common face. One of these has two internal resorption boundaries dividing it into three growth sectors (A, B, C Figure 26B). The outermost of these has a thin oscillatory zone at its outer edge Crossed-polar light. The crystal cluster is about 1.6 x 2.2 mm. in size. DDH 319-339.3
