About Slate
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 metamorphosis.
The result is a foliated rock in which the foliation may not correspond to the
original sedimentary layering.
Slate can be used for
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 and snooker table tops tops. In 18th and
19th century schools, slate was extensively used for blackboards and individual
writing slates.
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.
When broken, slate produces a natural appearance while remaining relatively
flat and can be easily stacked. Silicone glue adheres to slate, creating a
non-toxic bond to secure it.
Slate-producing regions
include
Slate is also found in the
Arctic and was used by the Inuit to make the blades for ulus.