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What is Slate?
Slate Stone
Slate Stone or simply slate is compact metamorphic
rock, composed primarily of silica and alumina. Slate is
easy to clean, requires very little maintenance and also
provides high slip resistance & is long lasting. Slate
tiles and slate slabs are suitable for exterior and
interior applications such as wall-cladding, roofing,
flooring, hearths, fireplaces, kitchen, landscaping,
driveways, pools, etc. Natural slate stone is known by
many names such as grey slates, flags, flagstones, thick
stones, slats, flat stones, stone tiles and tile stones,
as it imparts a majestic and spectacular look on the
buildings. Natural slate is available in a variety of
colors such as black slate, blue slate, red slate, grey
slate, green slate, etc.
Slate Finishes : Naturally non-slip surface can be
rubbed plain or finished with clear varnish after
fixing.
Slate Uses : Wall-cladding, roofing, flooring and all
other types of interior & exterior applications
depending upon the imagination of an architect.
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Slate is a fine-grained, homogeneous, metamorphic rock
derived from an original shale-type 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.|
Chemical composition
Slate is mainly composed of quartz and muscovite or
illite, often along with biotite, chlorite, hematite, and
pyrite along with, less frequently, apatite, graphite,
kaolin, magnetite, tourmaline, or zircon as well as
feldspar. Occasionally, as in the purple slates of North
Wales, ferrous reduction spheres form around iron nucelei,
leaving a light green spotted texture - the spheres
sometimes deformed by a subsequent applied stress field to
ovoids, which appear as ellipses when viewed on a cleavage
plane of the specimen.
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Uses of slate
Slate can be made into roofing slates, also called
roofing shingles, because it has two lines of
breakability: cleavage and grain. This makes it possible
to split slate into thin sheets. Fine slate can also be
used as a whetstone to hone knives. Because of its thermal
stability and chemical inertness, slate has been used for
laboratory bench tops and for billiard table tops. In 18th
and 19th century schools, slate was extensively used for
blackboards and individual writing slates for which slate
pencils were used.
Slate tiles are often used for interior and exterior
flooring or wall cladding. Tiles are installed and set on
mortar and grouted along the edges. Chemical sealants are
often used on tiles to improve durability and appearance,
increase stain resistance, reduce efflorence, and increase
or reduce surface smoothness. Tiles are often sold gauged,
meaning that the back surface is ground for ease of
installation.
Slate is often used as a decor in freshwater aquariums.
Slate will not alter the chemistry of water {except in the
slate containing feldspar which may leech silicates into
the water resulting in excess diatom growth in marine
aquaria). When broken, slate produces a natural appearance
while remaining relatively flat and can be easily stacked.
Silicon glue adheres to slate, creating a non-toxic bond
to secure it. It is also used in stairs and pathways for
the same reasons.
Traditional Go equipment uses slate for the black
pieces. |
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Slate extraction
Slate-producing regions include Cornwall (famously the
town of Delabole) and Wales in the United Kingdom (see
slate industry in Wales), Liguria in northern Italy
especially between the town of Lavagna (which means
chalkboard in italian) and Fontanabuona valley, Portugal
especially around Valongo in the north of the country,
Germany (Moselle River-region, Hunsrück, Eifel, Westerwald,
Thuringia, north-Bavaria), Alta, Norway, Galicia, Brazil
around Papagaio in Minas Gerais, the east coast of
Newfoundland, the Slate Belt of Eastern Pennsylvania, and
the Slate Valley of Vermont and New York. Granville, New
York, of the Slate Valley claims to be the colored slate
capital of the world.
Slate is also found in the Arctic and was used by the
Inuit to make the blades for ulus. China has vast slate
deposits; in recent years its export of finished and
unfinished slate has increased.
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Granite