Fig. 22. Albite-twinned plagioclase (light gray; center and top right) replaced by K-feldspar (dark gray; bottom right). Remnants of the plagioclase occur in the K-feldspar as perthitic stringers and have albite twinning that parallels the albite twinning in the plagioclase outside the K-feldspar (left center and top right). K-feldspar (light gray; upper left corner) replaces albite twinned plagioclase (dark gray), leaving tiny remnant islands of the plagioclase inside the K-feldspar in parallel optical continuity with the larger plagioclase crystal outside the K-feldspar. Pyramid Peak granite west of Lyons Lake. Thin section 165 from Loomis collection.