6 Things You Did Not Know That Cause Marble To Rust Plus Fix


Rust stains are a pretty common thing that occurs on marbles and most natural stones. But why does this happen? In this article, I’m going to share with you 6 reasons why marbles rust and some of the best ways to fix and prevent them.

So why does marble rust? There are so many peculiar factors that can contribute to your marble becoming rusty. Some the common reasons why marble can rust are due to;

  1. The Iron Deposits Contained In The Marble
  2. Rust Substances In Water Pipes
  3. Acid Rain
  4. The Marble’s Closeness To An Iron Metal
  5. Humidity
  6. Where The Marble Is Sourced

So there you have it if you came for a quick short answer. However, there’s certainly more to the above short answer. To learn more details about why marble rust, keep reading this article.

1. Marbles Contain Iron Deposits

Generally, marbles will comprise different components. Some of their main components are iron, bronze, and copper. While these different elements come together to form the marble we love and cherish, they are also among the main reason why marble is so easy to get rust stains – especially, white or light-colored marbles like Carara Marble.

The elements such as iron, bronze, or copper present in marbles will particularly cause them to stain when the marble becomes wet. Don’t let the glossy or shiny surface of the marble deceive you, marbles can easily get water stains due to their porous nature.

Yes, all it takes is for some water to consistently get seeped into the marble and get into contact with its elements, and boom, rust stains begin to appear on the surface of the marble.

As ironic as this may sound, this is one of the basic ways marbles rust. I know you might be thinking “doesn’t this sound contradictory to the overall purpose of a marble”.

Indeed, marbles are made to be used mainly around places where contact with water will be inevitable – so talk of bathrooms, kitchens, floors, etc, and your marble will have water on them in a twinkle of an eye.

Marbles are usually treated so that water does not get seeped through its pores to have contact with the elements in the marble that could cause the marble to rust.

But water will still seep through grout lines or around the faucet into the marble and the result, you guess is as good as mine.

The unfortunate part is, these rust stains because results from the internal iron compound of the marble it is incredibly difficult to remove – not even with a poultice made of baking soda and ammonia.

2. Rust Substances In Water Pipes

Tap water contains ingredients that generally make its pH levels safe for use on marbles. But water will continue to remain safe for marble if the minerals in the water running through your pipes remain what it’s supposed to be without any pollutants.

One of the common substances that tend to pollution tap water without our knowledge is rust-causing irons that come from old pipelines.

This is often the case in old buildings with very old metal pipelines. With such old pipelines, water running through will carry along with it rust substances.

When we open our taps to use the water, the water ends up on our marble surfaces, especially, parts close to the faucet and drains and they will begin to show signs of rust.

If not treated, the rust will worsen and spread terribly discoloring your marble surface. Rust will also be worse around parts of the marble that is far from the faucet and drains if those parts collect water.

If the place you live has very old metal pipes you would want to have it looked at and possibly changed as it is not only unhealthy for your marble surfaces but bad for your health as well.

You can verify if the water running through your pipes contains rust substances. You can ask for your water to be tested or have a plumber have a look at your pipes if they are rusty.

3. Acid Rain

Rust on outdoor marble installation can usually be attributed to acid rain which is caused by a chemical reaction that starts when compounds like nitrogen oxides and sulfur dioxide are released into the atmosphere.

The phenomenon does not end with these substances rising into the atmosphere alone but these substances after it has risen mix and react with oxygen, water, and other chemicals in the atmosphere to form an acidic pollutant, commonly known as acid rain.

Before I get off the boring science behind acid rain formation, it is important to add that when the pollutant acids fall back as rain, it usually has widespread impacts on a variety of elements in the environment such as our freshwater bodies, soils, forest, aquatic life, insects, and many others things in nature.

Acid rain does not only affect nature, but also, is responsible for causing the weathering of natural stone installations like marble, granite, limestone, etc, paints on buildings to peel, and steel structures like bridges to corrode.

One of the common effects of acid rain particularly on outdoor marble surfaces is the appearance of rust and discolorations on objects like statues, garden fountains, marble stairs, etc.

This is usually due to solubilized ions transported via rain onto the marble surface. Once acid rain has reached the marble surface, rust begins to form and the rest is history.

4. The Marbles Closeness To An Iron Metal

Another common cause of rust on marble surfaces is the marble’s closeness to iron metals. Marbles today are used in various ways and with a lot of different materials.

These materials will normally include woods, plastics, stainless steel, and metals. Wood, stainless steel, and plastics are fine, but those made of metals are not going to be best friends with your marble surfaces.

When marbles are installed with iron metal components, air can simply oxidize, and catalyst reactions between the marble and the metal causing the appearance of rust on the marble surface.

In the same way, water can also fuel a reaction between marble installed with iron metal components. Rust on the surface of marble can be a real pain so you would like to ensure your marbles are not installed with anything metal to be on the safe side.

Also, you do not want to store things made from iron metals close to your marble as water and air can oxidize and cause a reaction that can result in the appearance of rust.

5. Humidity

Marble is a natural stone but can still be somewhat fragile around the wrong conditions. One of the common conditions that promote the appearance of rust on the surface of the marble is humidity.

The kind of rust you will have from high humidity levels is indwelling rust that is impossible to remove. This is mainly caused by the constant induction of humidity usually from the backside of the marble stone.

There are instances where even the mildest form of humidity can also cause rust to appear marbles if the marble is not well protected or sealed.

So this begs the notion if mild or low humidity can cause rust to appear on marble, then you can imagine what can possibly happen with the levels of humidity generated in the bathroom and in the kitchen.

The result of humidity is not only rust but also severe discoloration that can range from yellow, brown, to orange.

Pro Tip: When your house, office, or facility is being installed with marble, one of the safest things you can do if you live in a very humid climate is to prevent the initiation of rust especially on your marble floors and walls is to keep a humidifier or air conditioner on during the installation of your marble or natural stone to regulate the humidity levels.

6. Source Of Marble Material

Some of the world’s best marbles are sourced from the Mountains of Carrara in the Apuan Alps. This is a mountain range located in Northern Tuscany.

The mountains of Carrara host over 180 quarries and account for one of the largest marble quarry sites in the world. This location is known to have the very best marble that Michelangelo himself from time to time, visited these quarries to handpick marble slabs for a lot of the masterpieces he made.

A lot of the marbles in the Mountains of Carrara are harvested in the deep mountain caves of Carrara. This is why marbles from Italy are pure and void of any impurities or substances that can subsequently cause discolorations or rust.

On the other hand, marbles sourced from other parts of the world apart from Italy are known to often have issues with rust due to where the raw marble materials are sourced and how they are processed.

How To Remove Rust From Marble

Although I have said several times throughout this article that rust is almost impossible to remove from marble, I will still recommend you try removing the rust from the surface of your marble before considering replacing the marble..

One of the best ways to remove general and tough stains from marble is by using a mixture known as a poultice that can be found at Amazon

Below are the things you need and the steps you’ll need to follow to try removing the rust stains from the surface of your marble.

Things Needed:

  • Natural Stone Cleaner
  • Ready-Made Poultice or a DIY Poultice from Baking Soda and Water
  • Plastic Wrap
  • Tape
  • Plastic Scrapper
  • Microfiber Cloth
  • Natural Stone Sealer


Step 1:

Prepare the surface of your marble with the rust stains. You would want to clean the marble surface as thoroughly as possible to remove any loose dirt, dust, or debris from the surface of the marble.

After the surface of the marble is thoroughly cleaned, you would want to make sure the surface thoroughly dries.

Step 2:

Mix the poultice stain remover or your DIY poultice mixture. If you’re making the poultice yourself you would want to make a paste-like consistency from baking soda and a small amount of water.

Personally, I prefer using ready-made poultice stain remover as they are chemically formulated to precisely tackle stubborn stains from natural stone surfaces.

You would want to mix the ready-made poultice stain remover according to the manufacturer’s instructions.

Step 3:

Cover the entire area of the rust stain with the poultice stain remover or mixture. Make sure to put a generous amount of poultice on the rust.

After you have applied the poultice mixture on the rusted areas of the marble, cover the poultice application with plastic wrap and tape off the edges to ensure the poultice retains its moisture for the longest possible time.

Step 4:

Now leave the application to dry completely for 24-48 hours. After the poultice dries, you can use a plastic scraper to scrape off all of the poultice residues.

Use a damp microfiber cloth to wipe off any excess poultice residue and leave the marble surface to dry.

After the marble dries and there are still rust stains, you would want to repeat the entire process one more time or a couple more times and see how the rust appearance improves.

Step 6:

Seal the marble surface with a natural stone sealer.

If you’re satisfied with the result you can continue using your marble. Otherwise, now will be the perfect time to toss it and get another installation in place bearing in mind all the possible factors that may have led the initial marble to rust.


Hi! I’m Kobby, one of the co-owners of favoredstoneguides.com and the newest house owner in town. I’m a huge fan of most things natural. Over here on this site, I'm happy to share all the exciting hacks, tricks, and tips I have learned and continue to learn each day about taking care of natural stones.

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