Figure F22. Photomicrograph in plane-polarized light of Sample 187-1157B-5R-1, 54-57 cm (see "Site 1157 Thin Sections"), showing a micritic calcite vein crosscutting clay-rich material adjacent to the basalt wall rock. Identifiable lithic clasts include altered and unaltered plagioclase. Note the thin sparry calcite vein that bifurcates, passing between the upper boundary of the micritic vein and the clay on one side and crosscutting the clay/basalt contact on the other. Note also the truncated plagioclase (Plag.) phenocryst (lower right). (The white space between the basalt and the micrite vein [lower right] is due to parting during preparation of the thin section and is not a calcite vein.)