Figure 2.

SEM image of a resin cast of an etch-pit network near the surface of a weathered Shap alkali feldspar. (Scale bar 20 μm.) The cast was made by impregnating the feldspar with Araldite resin under vacuum, curing, and dissolving away the feldspar in concentrated HF. The surface of the feldspar is off the bottom of the micrograph, and the image is of a pile of two-dimensional networks that have fallen over to lie on top of each other. Because the resin is flexible, parts of the networks are curved. The original etch-pits were developed on edge dislocations very nearly parallel to b (horizontal) and c (vertical) in the perthite contact plane close to 01 of the monoclinic feldspar.