Note 15 — Chapter XVII
Reading edition
Hard rocks are sometimes composed of different minerals, which are arranged in a way that reminds us of a bed of fallen leaves, and are called "foliated," from the Latin word folium, a leaf. Gneiss is a good example of a foliated rock. It is composed of the three minerals, quartz, felspar, and mica, arranged in this foliated manner. Mica schist, talc schist, and other rocks have a similar structure, and are sometimes briefly called "schists."