metamorphic rock with
intermediate between slate and
schist. Commonly formed by the
regional metamorphism of
tuff. Micas characteristically impart a pronounced sheen to rock
cleavage surfaces. Has phyllitic cleavage.
Source: Leet, L. Don. 1982.
Physical Geology, 6th Edition. Englewood Cliffs, NJ: Prentice-Hall
- a. A metamorphic rock, intermediate in grade between slate and mica
schist. Minute crystals of sericite and chlorite impart a silky sheen to
the surfaces of cleavage (or schistosity). Phyllites commonly exhibit
corrugated cleavage surfaces. CF: illite; phyllonite. AGI
b. A general term for minerals with a layered crystal structure.
c. A general term used by some French authors for the scaly minerals, such
as micas, chlorites, clays, and vermiculites.
Dictionary of Mining, Mineral, and Related Terms