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schist vs. gneiss

[shist] / ʃɪst /

noun

  1. any of a class of crystalline metamorphic rocks whose constituent mineral grains have a more or less parallel or foliated arrangement.

[nahys] / naɪs /

noun

  1. a metamorphic rock, generally made up of bands that differ in color and composition, some bands being rich in feldspar and quartz, others rich in hornblende or mica.