Fig. 1a. This photomicrograph shows a magmatic clinopyroxene granite north of Ausable Forks, New York, which contains coarse mesoperthite in a granulite facies. Where the granite is slightly-deformed, secondary albite-twinned plagioclase An₂₀ has replaced the K-feldspar (light gray) of the perthite leaving plagioclase lamellae sticking out like teeth of a comb into the secondary plagioclase. Note remnant plagioclase lamellae (cream-yellow) in secondary plagioclase (center, left).