What is Limestone?

Mary McMahon
Mary McMahon

Limestone is a type of sedimentary rock found in deposits all over the world and used in an assortment of ways. This rock is one of the most common forms of sedimentary rock, with an estimated 10% of sedimentary rock worldwide being composed of limestone. There are a number of different forms of this rock which come in an array of textures, colors, and appearances, and many people interact with products made from limestone on a daily basis.

The White Cliffs of Dover are limestone formations.
The White Cliffs of Dover are limestone formations.

Like other sedimentary rocks, limestone is formed by the slow deposition of sediments, and their subsequent compression. The bulk of the world's deposits are marine in origin, consisting primarily of the remains of plants and animals, including reefs, which were gradually deposited on the ocean floor and later compressed due to geological activity and the weight of subsequent layers of debris and the ocean itself. Limestone can also form very slowly through a process of leaching through mineral fields and deposition, as in the case of stalactites and other cave formations.

Limestone is quarried from the ground.
Limestone is quarried from the ground.

The key mineral present in limestone is calcium carbonate, but the rock is often mixed with other mineral impurities. These impurities can dramatically alter the texture of the rock, along with its color. As an example of the diversity of limestone, both chalk and marble are forms of limestone, even though these two rock varieties look and feel very different. In the case of chalk, the rock is soft, typically white, and crumbly, while marble is hard, with crystalline grains and an array of colors which commonly includes large seams of color.

The Durdle Door sea arch formed as the ocean eroded limestone along the coast of southern England.
The Durdle Door sea arch formed as the ocean eroded limestone along the coast of southern England.

Some limestones are composed of small grains of material which have been compressed, while others have crystalline structures upon magnification. These variations are influenced by the stone's formative processes, as is the color, which can be white, yellow, green, pink, cream, black, rust, brown, or any other color imaginable, depending on impurities. Seepage through deposits over the course of centuries can also cause color variations.

In the case of stalactites, limestone has formed very slowly through a process of leaking through mineral fields and deposition.
In the case of stalactites, limestone has formed very slowly through a process of leaking through mineral fields and deposition.

In addition to chalk and marble, some other well known varieties of this stone include marl, dolomite, and oolite. Limestone has historically been used in construction, as many varieties make excellent building materials. It is also used in the manufacture of cement and animal feed, and it may be involved in the preparation of printing plates and other industrial processes. Limestone is also of interest to paleontologists, because it often includes excellent examples of fossilized organisms which can be studied to learn more about the geologic record and the history of life on Earth.

The Washington Monument is a famous example of a structure made from limestone.
The Washington Monument is a famous example of a structure made from limestone.
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

You might also Like

Readers Also Love

Discussion Comments


@bluespirit - I have heard that rumor about limestone cleaning water, but I have not heard any research behind it.

Another fun fact about limestone (and since Kentucky has so much of it, I wonder if this idea didn't start there), you can buy limestone fireplaces! I do not know about their durability, but if you were looking for something different to do, a limestone fireplace might be just what you need!


Kentucky is regionally famous for its limestone and one of the bourbon distilleries in Kentucky touts that their bourbon is so good because it used water that has been cleaned via going naturally through limestone as if limestone acts as a large Brita filter for their water. Though I've always wondered if that was actually true - can limestone clean water naturally?


Is limestone the normal material used in flooring tiles like for a kitchen? I am looking to remodel my kitchen in the next couple of years, and I really love the look of the stone floors. I was never quite sure what kind of rock it was made from, but now I'm thinking it may be limestone tile.

When you go to buy limestone flooring, if that is what this is, is there anything in particular you should look for? Are there different levels of quality to the stone, or will one type install better than another? Finally, when you go to buy it, is it best to go to a normal home improvement or flooring store, or is there any way to get in direct contact with a limestone supplier who would sell something like this to you?


Does anyone know that different impurities can cause different colors in marble or other types of limestone? I would have to assume iron causes the rust color, but I don't know what could make any of the others.

Also, I know of a lot of marble structures, but are there any famous monuments or buildings that are made from regular limestone?


@Izzy78 - One thing I always remembered from my geology class is that granite is a type of igneous rock, which means it was formed from cooled lava. I agree, though, they are both similar given their uses.

I think limestone is fairly common through the whole United States. Most cities I know have some type of rock quarry where they can dig up limestone. I think it is just the normal base for most of our land. Once you get into more mountainous areas, especially the Appalachian Mountains, the limestone gets more obvious.

In a lot of places, you can identify limestone because it is much more resistant to erosion than the other rock types. Over thousands or millions of years, other rocks have been worn down leaving limestone features that can be really interesting to look at.

I don't know about famous quarries, since limestone isn't an extremely rare or valuable rock, but you are right about marble quarries. I think southern Europe has a lot of marble.


I didn't have a clue that limestone could be so much more than the grey or white, rough rock that you see a lot of monuments and things made of. I definitely didn't realize marble was a type of limestone. Does granite fall into the same category? It looks kind of like marble. If not, what kind of rock is granite?

When we moved into our new house, we installed a new fence that is made of limestone slabs. It really looks great, and it will definitely be able to last as long as we need it to.

Where is limestone typically found? The article mentions it is common around the world, but are there certain areas that are famous for limestone production? I know there are famous marble quarries. Is there anywhere in the United States or Canada that have a lot of quality, natural limestone that is mined?

Post your comments
Forgot password?