Phyllite - an overview | ScienceDirect Topics
Phyllite is a foliated metamorphic rock rich in tiny sheets of sericite mica. It presents gradation in degree of metamorphism ranging between slate and mica schist. The color varies between black and gray to greenish-gray (Fig. 7.11).The phyllite forms from pelitic sediments (shale and mudstone) at a slightly higher degree of regional metamorphism from slate (Table 7.1).