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Cleavage (rock) identification and geology
A type of secondary foliation in metamorphic rocks formed by the parallel alignment of platy minerals micas, chlorite or by the dissolution and removal of material along closely spaced planes. Rock cleavage develops perpendicular to the direction of maximum compressive stress and is distinct from mineral cleavage. Slaty cleavage, crenulation cleavage, and spaced cleavage are recognized subtypes. Field: structural geology. Example: Welsh roofing slate splits along planes of slaty cleavage that developed perpendicular to tectonic compression during the Caledonian orogeny, independent of the original sedimentary bedding.. Related terms: Foliation, Schistosity, Slate, Metamorphism.
Sources, scope & corrections
These authoritative resources support category-level nomenclature, terminology, identification methods, and safety. When a specimen-specific safety warning appears, the public-health source listed here directly supports that precaution. They are not line-by-line citations for every other property on this entry, and natural specimens vary.
- Editorial owner
- GeoMiner
- Last updated
- 2026-03-30T15:19:41.970235+00:00
- Review status
- Published; not independently peer-reviewed
- USGS Thesaurus — U.S. Geological Survey. Controlled earth-science terminology used to describe USGS information resources.
- Glossary of Geologic Terms — U.S. National Park Service. Geologic definitions prepared by the NPS Geologic Resources Inventory.
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