Definition
Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism
Tonalite is a coarse-grained plutonic rock consisting mainly of sodic plagioclase, quartz, and hornblende or other mafic minerals with phaneritic texture
History
Origin
England
Tonale, Italy
Discoverer
Abraham Gottlob Werner
Warren Hamilton
Etymology
From Old French esclate, from esclat (French éclat)
From Tonale Pass, northern Italy, + -ite1
Class
Metamorphic Rocks
Igneous Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Hard Rock
Family
Group
-
Plutonic
Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock