Answer:
Principal characteristics of a slate are:
It's a Metamorphic rock
As e metamorphic rock it is Foliated
It's origin is Regional metamorphism
Is a fine-grain rock, for that reason it has non-visible minerals
A slate is composed by principally by clay and Micas.
Step-by-step explanation:
Slate rocks are fine-grain metamorphic rocks which original rock use to be a shale or a vocanic rock. It is foliated, becase of compression stress produced by regional metamorphism, it means, orogenic metamorphism common in compresive plate boundaries. The foliation are planes perpendicular to the stress direction. It has non visible minerals because of the size of it's original components; usually it comes from shales, sedementary rock with clay minerals that after metamorphism sometimes become micas.