Figure 3-1. High-magnification view of the contact (small red arrows) between two quartz grains at a stylolite shown at lower magnification in another image. Small opaque grains (probably pyrite) are trapped as residue between the quartz grains, which are in turn part of the general residue at the stylolite. Large arrow in A points to lamellar structures in upper quartz grain where the two grains have slipped past each other. B shows the area at the large red arrow in A, but rotated under crossed polars; large red arrow in B points to same segment of contact as in A. Note that the area of lamellae has a different optic orientation than the rest of the upper grain, suggesting that the grain's lattice has undergone strain at the stylolite. .

      Photomicrograph was taken in cross-polarized light. Field of view in A is 0.40 mm wide; field of view in B is 0.15 mm wide. Roadcut on US 322 bypass outside State College, Pennsylvania; Sample PA4-2; thin section S-1-146. Sample collected by L. Bruce Railsback.

   
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