STONE
CLASSIFICATION PROGRAM
SURFACE TYPES DEFINED
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SPECIAL
NOTE
Surface pitting, spawling and fissures are
a natural characteristic of all varieties of stone. Many imperfections
are acceptable in the industry when specifiers, fabricators, and
installers have a full understanding of natural stone and the
classifications listed below. Under any circumstances, if the
characteristics are in question, please contact a representative
prior to specification or installation.
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GRANITE |
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Granites
usually have been classed as igneous rocks derived from, molten
masses or magmas, but there is wide evidence that the origin of
some granite may be attributed to regional metamorphism or preexisting
rocks, rearrangement and recrystallization taking place without
a liquid or molten stage.
Granite is classified in three different groups as follows:
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- FINE
GRAIN:
Fine grain granites are those which the
feldspar crystals average about 1/16 - 1/8" in diameter
- MEDIUM
GRAIN:
Medium grain granites are those in which
the feldspar crystals average about 1/4" in diameter.
- COARSE
GRAIN:
Coarse grain granites are those in which feldspar crystals average
1/2", and greater diameter or several centimeters in maximum
dimension. Coarse grain granites may have a lower density.
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LIMESTONE |
Limestone
is defined as a rock of sedimentary origin composed principally
of calcium carbonate or the double carbonate of calcium and magnesium,
or a combination of these two minerals.
Recrystallized limestones, compact microcrystalline limestones,
and travertines that are capable of taking a polish are promoted,
marketed and sold as either limestone or marble, particularly in
the United States.
Dimension limestone is divided into three subclassifications that
describe their densities in approximate ranges, as follows: |
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- LOW
DENSITY :
Limestone having a density ranging from
110 through 135/lb/ft3 (1760 through 2160 kg/m3).
- MEDIUM
DENSITY:
Limestone having a density greater that
135 and not greater than 160 lb/ft3 (2160 through 2560 kg/m3).
- HIGH
DENSITY:
Limestone having a density greater than 160 lb/ft3 (2560 kg/m3).
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| NOTE:
Limestone contains a number of distinguishable natural characteristics,
including calcite streaks or spots, fossils or shell formations,
pit holes, reedy formations, open texture streaks, honeycomb formations,
iron spots , travertine-like formations and grain formation changes.
One or a combination of these characteristics will affect the texture.
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MARBLE |
Marble
is a metamorphic rock resulting from the recrystallization of limestone.
Commercially, however, all calcareous rocks produced by nature and
capable of taking a polish are called marbles, as are some dolomitic
and serpentine rocks. (See "Glossary" for clarification.)
The groupings - A, B, C, and D - should be taken into account when
specifying marble, for all marbles are not suitable for all building
applications. This is particularly true of the comparatively fragile
marbles classified under Groups C and D, which may require additional
fabrication before or during installation.
These four groups are: |
- GROUP
A: Sound marbles with uniform and favorable working
qualities; containing no geological flaws or voids.
- GROUP
B:
Marbles are similar in character to the proceeding group, but
with less favorable working qualities; may have natural faults;
a limited amount of whizzing, sticking and filling may be required.
- GROUP
C: Marbles
with some variations in working qualities: geological flaws,
voids, veins and lines of separation are common. It is standard
to repair these variations by one or more of several methods-whizzing,
sticking, filling or cementing. Liners and other forms of reinforcement
are used when necessary.
- GROUP
D:
Marbles similar to the preceding group, but containing a larger
proportion of natural faults, maximum variations in working
qualities, and requiring more of the same methods of finishing.
This group compromises many of the highly colored marbles prized
for their decorative values
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| The
Soundness Classifications merely indicate what method and amount
of repair and fabrication is necessary prior or during installation,
as based on standard trade practices. |
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SLATE |
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shales from which slate originate were deposited previously on clay
beds. Subsequent earth movements tilted these beds of shale, at
first horizontal, and the intense metamorphis that converted these
into slates folded and contracted them. Slate, then, belongs to
the metamorphic group of rocks and can be defined as a fine grain
rock derived from clays and shales and possessing a cleavage that
permits it to be split into thin sheets. |
- INTERIOR:
use only slates are designates with an
"I" or "interior" on specification sheets.
- EXTERIOR:
use is labeled as either "E"
or "exterior" on specification sheets.
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VARIATIONS |
| Numbers
such as 1, 2 or 3 often categorizes stones. These numbers pertain
to their color variations. |
- Limited
color variation:
Relatively uniform in background / field colors, veining and/or
movement.
- Moderate
color variation:
Background color has some variation and veining / movement variations
may appear. Inspection / blending prior to installation is suggested.
- Extreme
color variation:
Background color has significant variations and contrasts. Veining
variations movement may be inconsistent. Inspection / blending
prior to installation is strongly recommended.
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DISCLAIMER
Prins Custom Counter Tops does not guarantee
or warrant the provided ratings or classifications as shown. Various
resources accredited in the stone industry have provided these classifications.
Please request specification data when necessary.
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