smooth rock, usually dull blue or grey in color, which is split into
thin panels and used as a roofing or flooring material.
Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an
sedimentary rock composed of clay or volcanic
ash through low-grade
regional metamorphism. The result is a foliated rock in which the foliation
may not correspond to the original sedimentary layering. When expertly
"cut" by striking with a specialized tool in the quarry, many slates
will form smooth flat sheets of stone which have long been used for
roofing and floor tiles and other purposes. Slate is frequently grey in
color, especially when seen, en masse, covering roofs. However, slate
occurs in a variety of colors even from a single locality; for example,
slate from North Wales can be found in many shades of
grey, from pale to dark, and may also be purple, green or cyan. Slate
is not to be confused with shale, from which it may be formed, or schist.
Ninety percent of Europe's natural slate used for roofing originates
The word "slate" is also used for some
objects made from slate. It may mean a single roofing slate, or a writing slate, traditionally a small
piece of slate, often framed in wood, used with chalk as a notepad or
noticeboard etc., and especially for recording charges in pubs and
inns. The phrase "clean slate" or "blank slate" comes from this use.
In rural valuations slate country is poor sedimentary or "trtap" country with slate rock outcrops.