Slate

Slate is a fine-grained, homogeneous, sedimentary rock composed of clay or volcanic ash which has been metamorphosed (foliated) in layers (bedded deposits). Slate can be made into roofing slates (sometimes called 'roofing shingles' in the United States), because it has two lines of breakability: cleavage and grain. This makes it possible to split slate into thin sheets.

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Fine slate can also be used to hone knives.

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Slate is mainly composed of quartz and muscovite (a mica), often along with biotite, chlorite, and hematite, or, less frequently, apatite, graphite, kaolin, magnetite, tourmaline, or zircon.

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Some of the finest slates in the world come from Portugal, Wales in the United Kingdom, the east coast of Newfoundland, and the "Slate Valley" of Vermont and New York.

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Sedimentary rock: Sedimentary rock is one of the three main rock groups (along with igneous and metamorphic rocks) and is formed in three main ways—by the deposition of the weathered remains of other rocks (known as clastic sedimentary rocks); by the deposition of the results of biogenic activity; and by precip...

Clay: :For the town in the United States, see Clay, New York....

Volcanic: REDIRECT Volcano...

Slate related Images and Photos (experimental)

Hollywood Slate Board	Sons of Anarchy Slate Grey Reaper T-Shirt	Dark-Eyed or Slate-Colored Junco Junco Hyemalis North America	Warner Bros. Vintage Logo Adult Slate Blue T-Shirt
Hogan's Heroes: 'Hogan!' T-Shirt - Slate	Hogan's Heroes: 'Hogan!' T-Shirt - Slate	Happy Days ' The Fonz ' T-Shirt - Slate	Happy Days ' The Fonz ' T-Shirt - Slate
Celtics Banner '47 Scrum T-shirt - Slate	Star Trek 'Running Cartoon Crew' T-Shirt - Slate	Star Trek Running Cartoon Crew T-Shirt - Slate	Star Trek 'Running Cartoon Crew' T-Shirt - Slate