slaty cleavage

geology

Also known as: slaty foliation

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July 13, 2026

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Slaty cleavage is a fundamental characteristic of slate, a fine-grained metamorphic rock. This geological term describes the rock's ability to split readily into thin, durable slabs. Unlike sedimentary rocks that split along their original bedding planes, slates cleave along planes of induced pressure, which can intersect the bedding at high angles.1

This cleavage is a result of low-grade metamorphism, where pressure causes the alignment of minerals like mica and chlorite. The direction of this cleavage is determined by the stresses applied during the metamorphic process. This property makes slate valuable for roofing, electrical panels, and blackboards.12

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metamorphic rock
Major features
…s-surface, bedding, or crystal orientation; slaty cleavage, a planar structure leading to facile cleavage that is normally caused by the preferred orientation of mica crystals; schistosity, a term used to describe repetitive and pronounced foliation of the type that is present in schists; and lineation, which is any linear structure,…
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…s-surface, bedding, or crystal orientation; slaty cleavage, a planar structure leading to facile cleavage that is normally caused by the preferred orientation of mica crystals; schistosity, a term used to describe repetitive and pronounced foliation of the type that is present in schists; and lineation, which is any linear structure,…
Read More