Simple Lithology

slate

http://resource.geosciml.org/classifier/cgi/lithology/slate

definition compact, fine grained rock with an average grain size less than 0.032 millimeter and a well developed schistosity (slaty cleavage), and hence can be split into slabs or thin plates. more like this
source NADM metamorphic rock vocabulary SLTTm1.0; Neuendorf et al. 2005 more like this
type
Resource
Concept
broader foliated metamorphic rock
narrower slate
in scheme simplelithology
is primary topic of slate