Natural Limestone

Composition of Natural Limestone

Limestone is a calcareous natural stone that is composed of at least 50% calcium carbonate in the form of calcite by weight. It can contain other minerals as well but it is made up of mostly calcite. Here are some of the components than can be in limestone:

• CaCO₃ (Calcium Carbonate)
• MgCO₃ (Magnesium Carbonate)
• SiCO₂ (Silica)
• Al₂O₃ (Alumina)
• Fe₂O₃ (Iron Oxide)
• SO₃ (Sulphate)
• P₂O₅ (Phosphorus)
• K₂O (Potash)
• Na₂O (Soda)

Natural Limestone Characteristics

Depending on the amount of and type of impurities in a given limestone slab, it can range from white to various shades of grey or tan in most cases. However, limestone can occur in varous colors. The porosity of a particular stone can vary depending on the composition. Additionally, limestone normally has a hardness ranging from 2 to 4 on the Mohs scale of mineral hardness.

Applications and Uses

Limestone has been used for many years in a number of ways.

Advantages of Natural Limestone

One advantage to using limestone, particularly for flooring, is that it is porous. This can translate into a non-slip surface, depending on the finish and surface treatment that is or is not applied.

Compared with other natural stone types, limestone is less costly. It also offers a distinguished look and in some cases, an unmistakeable beauty. An example of this is in the case of travertine. Travertine is a very distinct looking limestone that has a character all its own.

Limestone's Disadvantages

One drawback to using limestone is that it is a calcareous stone. Calcareous stone is stone that contains calcite. Calcite (a form of calcium carbonate, or CaCO ₃) is susceptible to acids. In addition to acid susceptibility, limestone is also a relatively heavy stone. Another, disadvantage to limestone is that it is a relatively "soft" as far as stone goes. It is also porous, which means it can be susceptible to staining via liquid substances. Yet, there are ways to care for and maintain limestone.

Care and Maintenance

Caring for natural limestone is simple. However, simple does not necessarily mean it is easy. Since limestone is calcareous (composed of calcite), it requires immediate clean up of acidic liquids that could mar the appearance if not removed right when the spill happens. Additionally, regularly sealing limestone can help protect it from staining that could occur from colored liquid that could get into the pores of the stone and discolor it. Here are some practical steps that can be taken to care for and maintain natural limestone.

1. Make sure to initially seal limestone countertop surfaces to help them resist stains from oil and water based liquids.
2. Use a pH neutral cleaner when cleaning your limestone surfaces. Acidic cleaners breakdown the sealer.
3. Periodically use an impregnating sealer to renew the seal that was added right after the install.

In addition to the care tips above, you can use a fortified natural stone polish on the surface of natural limestone countertops (not flooring) to build up the seal a little at a time. By using the pH neutral stone cleaner and natural stone polish, you can consistently maintain the appearance of your limestone surfaces.

With limestone there is also a need to have an effective etch remover on hand to care for etching that can occur on limestone surfaces. Etching occurs when acid dissolves the calcite in the limestone, leaving a dull spot.

As we have seen, limestone is a very practical natural stone that can be used for a number of applications. It offers advantages as well as some drawbacks. The beauty and cost effectiveness of limestone though, may make it a good choice for some of your projects.