Fig. 20. Microcline (black and white; grid-twinned; lower left side) is in the process of replacing the interior of an albite-twinned plagioclase crystal (tan) toward the right. Microcline (upper right) also replaces the same plagioclase crystal in the opposite direction. Rim myrmekite and cataclastic fragments of remnant plagioclase occur along the border between the microcline and the plagioclase. Pyramid Peak granite west shore of Smith Lake. Thin section 131 from Loomis collection.