Jura Grey Limestone floor tiles by S & N Brothers with a polished finish
Limestone is a sedimentary rock composed largely of the mineral
calcite (calcium carbonate: CaCO3). Limestone often contains variable amounts of
silica in the form of chert or flint, as well as varying amounts of clay, silt and
sand as disseminations, nodules, or layers within the rock. The primary source of
the calcite in limestone is most commonly marine organisms.
These organisms secrete shells that settle out of the water column and are deposited
on ocean floors as pelagic ooze or alternatively are conglomerated in a coral reef.
Another form taken by calcite is that of oolites (oolitic limestone) which can be
recognized by its granular appearance. Limestone makes up about 10% of the total
volume of all sedimentary rocks.
Pure limestone is almost white but due to impurities, such as clay, sand, organic
remains, iron oxide and other materials, many limestones exhibit different colors,
especially on weathered surfaces. Crystals of calcite, quartz, dolomite or barite
may line small cavities in the rock. During regional metamorphism that occurs during
the mountain building process (orogeny) limestone may recrystallise into marble.
Calcite can be either dissolved by groundwater or precipitated by groundwater,
depending on several factors including the water temperature, pH, and dissolved
ion concentrations. Calcite exhibits an unusual characteristic called retrograde
solubility in which it becomes less soluble in water as the temperature increases.
When conditions are right for precipitation, calcite forms mineral coatings that
cement the existing rock grains together or it can fill fractures.
Bands of limestone emerge from the Earth's surface in often spectacular rocky
outcrops and islands. Examples of tourist renown places include the Burren in
Colorado; Clare in Ireland; the Verdon Gorge in France; Malham Cove in North
Yorkshire and the Isle of Wight, England; on Fårö near the Swedish island of
Gotland, the Niagara Escarpment in Canada/USA, Notch Peak in Utah, Rajasthan
in India and the Ha Long Bay National Park in Vietnam. There are of course many
other locations with less of the tourism aspect of some locations such as Solnhoffen
in Germany, South Australian coast, Limestone deposits in Peru and Ontario Canada;
the Iberian Peninsula; and Mount Saint Peter quarries in Belgium / Netherlands that
extends for more than a hundred kilometers.
For further information contact:
S & N Brothers
phone: 02 9793 2001
fax: 02 9793 2002
web: www.snb-stone.com
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