About Natural Limestone
In the realm of architecture natural stone is featured in a variety of projects and in a variety of ways. This natural stone offers a number of significant benefits and its properties make it the choice for some very specific surfaces. In this post we will look at natural limestone. We will not only discuss what it is and how it is formed, but we will also look at what needs to be considered when working with it. Additionally, we will consider how to care for and maintain limestone surfaces.
What is Limestone
Limestone is a sedimentary rock consisting of at least 50% calcite or calcium carbonate content. However, a large portion of commercial limestone contains much more than 50% calcium carbonate. Most limestone is made up of organic material such as that found found in fossils and even bone fragments. Because of the variety of limestone types, it is not uncommon to see a descriptive term used in conjunction with the worked limestone to describe the stone more fully. Some examples of limestone names with descriptors include:
- Conglomeratic Limestone
- Muddy Limestone
- Pebbly Limestone
- Sandy Limestone
- Shaly Limestone
- Silty Limestone
Colors of Limestone and Veining
Natural limestone is often times very light (close to if not white) in color with various shades of other (darker) colors accenting the main color. These color variations are caused by a range of substances that are included in small quantities during the formation of the rock. One of the “impurities” affecting the color of limestone is Iron Oxide, which can produce the following colors:
- Pink
- Yellow
- Brown
- Red
In addition to Iron Oxide, there are also substances of bituminous origin that produce the following colors:
- Gray
- Blue-gray
- Black
Limestone has been around for a number of years and can be been featured in a variety of architectural and construction projects.
Finishes
Not much to say here, except that limestone is finished in a variety of ways. Some of these include:
- Abrasive
- Antiqued
- Bush-hammered
- Flamed
- Honed
- Plucked
- Polished
- Sawn
- Smooth
- Tumbled
A brief note though on finishes. Some finishes (e.g. thermal and tooled) can impact the strength and/or durability of the stone.
Limestone Flooring
One of the favorable uses for natural limestone is flooring. Natural limestone floors are impressive, pleasing to the eye and durable. When used in the proper environment, natural limestone lasts a lifetime. Professionals use this resilient natural stone not only for flooring, but also for facades, cladding and staircases.
Working With Limestone
Limestone is a relatively “soft” stone; registering between 3 and 4 on the Mohs scale of mineral hardness. Because of its properties, limestone has some specific requirements that fabricators should know when working with it. First, the high calcite content of limestone means it can be damaged through content with acidic liquids. Acid dissolves calcium carbonate and therefore should not be used on limestone.
Second, because limestone is soft, it is recommended that an appropriate diamond blade be used to cut limestone. Using the wrong blade can cause the blade to get clogged with material suring cutting. Using a marble blade for cutting limestone is generally a good option.
Limestone Care and Maintenance
Like any natural stone, limestone is porous. As a result, it absorbs liquid substances. Therefore it is necessary to seal it so as to slow the absorption. Colored liquids that get into the pores of limestone can cause staining; requiring a stain remover to clean up the surface.
In addition to staining, limestone surfaces can become “etched”. Etching is the deterioration of the calcite in the stone by acidic liquids. Restorers remove etching with an etch remover on the surface of the stone.
In conclusion, limestone is a very practical natural stone that has been used in a variety of applications and is available in various colors (although most limestone is white gray and beige in color) and works well for projects that need to be able to last.