Marble

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General Description

Marble is a metamorphic stone. It was at one time a limestone or dolomite that has been structurally altered by recrystallization. Pure marble is white. The abstract variety of colors, mottling, clouds, swirls, shadings, streaks and veining are derived from the accessory minerals that were present in the limestone or dolomite.

Group

Metamorphic

Common Rock-Forming Mineral Group

Calcareous

Composition

Calcite, dolomite or a combination of both and accessory minerals acting as coloring agents. Veining minerals range from calcite, quartz and a variety of other minerals.

Constituent
%
CaO 53.70-55.90
CO2 42.17-53.54
MgO 0.06-0.92
Al2O3 0.06-0.94
Fe2O3 0.005-0.42

 

Hardness

Soft/ Medium/ Hard

Porosity%

0.12 – 2.3

Density

2.4-2.8 gr/cm3

Abrasion Resistance

0.25-2.9 mm

Compressive Strength

27-159.7 MPa

Mohs’ Scale

3 – 5.5

Absorption %

0.1 – 0.6

Coefficient of Linear Expansion

2.7-5.1/ºC x 10-6

Flexural Strength

6.15-21.4 MPa

Specific Gravity

2.64-23.73 kg/m3

Impact Strength

21.20-60 cm

Weight

2651.55-2731.90 kg/m3

Weathering Characteristics

Moisture sensitive as a rule. All polished marble will lose their polish in exterior applications.

Tendencies

  • Absorbs oils and other liquids
  • Easily scratched
  • Acid sensitive
  • Stone fasades need periodic cleaning if good appereance is to be preserved. Dirt deposit includes soot, wind-blown smoke, exhaust from vehicles may affect the surface cleaness.
  • Staining may be caused by organic growth, urban grime or metal run off. Growths may be treated by toxic washes, metal stains may be more difficult to treat.

Acid Resistance

Acid gases such as sulphur dioxide attack stones containing carbonate material such as calcite and dolomite. This may leads to either erosion causing surface loss or crystalization damages.

Colours

Every colour is possible due to the variability of accessory minerals.

Finishes

Polished,Honed

Thickness

10-15 mm for internal wall; up to 20mm for floor.

External wall cladding: min 25-30 mm.

Treatment

It’s important to ‘seal’ or impregnating, to ensure it can last to its maximum life-span, i.e. to avoid scratch, water penetration, stains, etc. This usually done before installation on the 5 sides (front, and 4 sides) of the individual cut-panel, or even 6 sides (includes the back side).

When necessary, some treatments should be involved, such as color enhancer, anti slip resin, etc.

Notations

Some marbles are more moisture sensitive than others, Creme Marfil, Perlino Rosata, Bottiocins, Breccias some Perlatos and Rosa Veronas, and some are extremely moisture sensitive, as a rule the red, black and green marbles. This color group of marbles may present problems such as warping, blistering,and spalling when installed with setting materials containing water. It is strongly recommended that the use of a water free epoxy adhesive be used with black and green marbles. Marble used in the kitchen should be carefully evaluated due to its acid sensitivity. Treating marble with a water or oil repellent is highly recommended.