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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
From Old French esclate, from esclat (French éclat)
Durable Rock, Medium Hardness Rock
Fine Grained Rock, Opaque Rock
Novaculite is a dense, hard, fine-grained, siliceous metamorpic rock which is a type of chert that breaks with conchoidal fracture
From Latin word novacula, for razor stone
Fine Grained Rock, Opaque Rock