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Technical Information - Limestone
Limestone
is considered the most abundant chemical sedimentary rock. Many
different types exist, yet the mineral composition of all
limestone is similar. Most of them are of marine origin, formed in
ancient warm shallow seas directly and indirectly from the life
processes of marine plant and animal organisms.
|
GROUP |
Sedimentary |
|
COMMON
ROCK-FORMING
MINERAL
GROUP |
Calcareous |
|
COMPOSITION |
Calcium
Carbonate (Calcite) or the double carbonate of Calcium and
Magnesium
(Dolomite). Contains a variety of accessory minerals...silica,
pyrite, iron oxides, clay minerals and bituminous matter from
organic materials (plant & animals). |
|
HARDNESS |
Soft
to Hard. Some varieties are as hard and dense as granite.
|
MOHS'
SCALE |
2 - 5 |
|
POROSITY
% |
0.6 - 31.0 |
ABSORPTION
% |
0.2 - 12.0
|
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WEATHERING
CHARACTERISTICS |
Depends
on the environmental conditions and the type of limestone...Exterior
installation, in warm humid regions limestone weathers easily.
If iron oxides or pyrite are present rust spots or runs may
appear and if it contains bituminous matter dark blotchy spots
or runs also may appear. |
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TENDENCIES |
Absorbs
oils and other liquids...Softer varieties
have low scratch resistance.
Acid sensitive as a
rule. However, the Dolomite Limestone varieties are least
affected...Some varieties have large pores
while others have an open pitted textured surface capable of
catching and holding dirt and soil. |
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COLORS |
Range
is in the pastel colors from white to creams through beige to
pinkish...soft yellows through browns to rich
crimson...medium green to dark blue-green...gray
to black. Patterns vary from solid to variegate. |
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FINISHES |
Any
finish that is available is possible, depending on the variety...
Not all limestone's can be
polished. As a general rule the lower the clay and silica
content the better the limestone will take a polish. |
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NOTATIONS |
Due
to the high absorption factor of the majority of
limestone's it is
highly recommended for practical maintenance considerations
and to minimize staining, that the stone be treated with a
water and or oil repellent...It is important
when choosing the treatment product that the solid content be
carefully evaluated or a treatment product that has been
specifically formulated for large pored stones be used. Some
limestone's surfaces will roughen over time. This is not a
form of decay, but merely the surface of the stone developing
a natural patina. |
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Commercially
those Limestones’s that can be polished have been classified as a
"Marble" and are sold as such. It can be very difficult to
visually distinguish some of these limestones from a true
metamorphic marble.
With its
unique characteristics, subtle beauty and great versatility have
made it a
popular
choice for any design style.
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