Basalt: The Puzzling Stone

BASALT: the Puzzling stone

By Mark Ortiz, Stone Restoration Specialist

This months subject is about a puzzling stone on the market and why it is so. As with many new stones on the market, it takes a while until we get a better understanding of their nuances. Coca Cola used to say in it’s marketing ads, “There is nothing better than than the real thing.”  I agree, but to appreciate and promote the real thing about stone, we need to learn as much about it as possible.


Before you read on with my perspective of how Basalt is used, I’ve attached a 2 minute YouTube link to a geological understanding of Basalt in its natural environment. Nick loves natural stone. If I ever retire this may be me one day!

You cannot tell me that wasn’t a pretty cool video of the formation of Basalt. Like all natural stones, it's an amazing work of God's creation that we get to gaze at, touch and use in multiple ways in our own homes and businesses. Let’s see what our geologist professor tells us what about Basalt.



What is Basalt?


Basalt is a mafic extrusive igneous rock formed from the rapid cooling of magnesium-rich and iron-rich lava exposed at or very near the surface of a terrestrial planet or a moon. More than 90% of all volcanic rock on Earth is basalt. It is a fine-grained substance with varying shades of color from grey to black. Basalt is an intergalactic rock as well with samples found on Earth’s moon, Mars, Venus and on several asteroids. Most of the ocean’s floor is composed of basalt rock.



Here is my wife Kerri and me at T-Rocks, a cool place in Quartzsite Arizona just past the California Arizona border. We always stop at this place to look at minerals and rocks on our way to see family in Mesa. I’m holding a piece of Basalt.




What are the benefits of Basalt?


Every stone has benefits, whether it’s based on color, design, practicality or durability. In my experience, I have noticed Basalt best used in dry locations such as walls, veneers, floors and fireplaces. It’s a hard stone meaning it doesn’t scratch easily from normal use. Because of its monochromatic charcoal to black color it can be used in multiple applications for both the residential and commercial industry. Being volcanically formed it is also able to withstand tremendous amounts of heat.



What are the concerns?



Since the stone is very porous, it stains easily. When Basalt stains, the stone creates black spots or markings. Imagine if Basalt was on a kitchen floor and after a zinger of a party you wake up to see hundreds of dark spots that do not clean up! This is common for Basalt flooring in high use areas or areas with high oil exposure. Basalt dries out pretty well when exposed to water so showers should not be a problem, right? Wrong.  Soaps, oils and other liquids often used in showers can stain and leave permanent discoloration. Shower walls are usually ok, but benches and floors stain easily.




 What is the Solution?


Perfect Granite Solutions is in the business of finding solutions for stone problems and providing long term maintenance care. The first defence is to avoid applications that will easily produce stains.


Areas not recommended by PGS:

  • Kitchen counters and floors
  • Laundry counters and floors
  • Bathroom counters and showers
  • Restaurants or Salons

I know that seems like a lot of areas but these are the common areas that I see the most problems. These other areas are beneficial, wear well and look amazing.


Areas PGS recommends:

  • Exterior Flooring
  • Interior flooring ( not in bathrooms or kitchens )
  • Walls, wainscot, veneers, exterior wall caps
  • Fireplaces
  • Commercial lobby floors

Does Sealing Help?


Sealing is the best protection against staining on Basalt, but let me assure you, that almost all penetrating / impregnating sealers on the market are ineffective against the porosity of Basalt. We have tested the “best” penetrating sealers with aggressive testing and all failed! That's right, all.  I’m not one who sells sealer therefore I have no bias towards one over the other. Quality penetrating sealers are intended help prevent staining, therefore we encourage sealing, More effective then penetrating sealer are topical sealers. Topical sealers provide a barrier on the stone protecting it from staining. Floors and locations exposed to water and soaps should be sealed with a topical sealer. Testing is important because many of the sealers are too glossy or make it darker. This leads us to Enhancers.



Enhancer Sealers


A proven solution to appreciate basalt is sealing with a stone color enhancer. When the stone discolors from oils or liquids, it turns dark or black. Since the stone is already dark (charcoal / black) after enhancing. the staining is less obvious. This is very effective, but samples should be provided to ensure the customer accepts the dark color. Once you apply an enhancer, it is permanent and cannot be removed.


Why do new installations look blotchy?


New installations often look blotchy, inconsistent, vary in color shades and mark up easily from either installation, construction trades or it just came in that way. Cleaning doesn’t often solve the problem, nor does sealing. If a new installation is too blotchy, we have to lightly refinish the stone to create an even finish. Once the stone is refinished then we go back and look at the options of sealing or enhancing.


Basalt had been pretty challenging for us since it first came on the market, but we have been able to solve the problems and better communicate with the customer. If I was selling or installing stone to clients, I would say something like the following.

“ Basalt (or Lava Rock) can be one of the coolest stones to look at but if you are not aware of its characteristics it can be challenging right from the beginning. Because it is very porous, we recommend avoiding installations where high water, soaps and oils are present, such as kitchens, showers and commercial restaurants. In addition we highly recommend it to be either enhanced or sealed topically. Consulting a professional sealing company will ensure the best possible protection and maintenance is provided.”





It is almost impossible to describe the actual results or how effective the sealer will be for Basalt. Bring us samples of the Basalt you are going to use and I will do some samples for you to test the effects of staining liquids. Our experience with customers after Basalt was installed is usually less than satisfied when it comes to practicality. After education and proper treatments are applied, we usually help them become more accepting of their stone. Consider how we can help you on your next Basalt project.




Pass this useful information to your staff and everyone associated with the stone industry. Let us know if you want to be added to our Monthly Education Newsletters.


Do you have a topic that the industry needs to know about? Email it to me:

Write a comment

Comments: 16
  • #1

    Wendy (Sunday, 17 May 2020 15:13)

    Hi, I am in a quandary. I have a new natural basalt outdoor wall fountain, with a planter wall with basalt capstones. The stone is not sealed. The stone is turning yellow where the fountain water cascades down the front. I presume it is algae, although I always thought algae was green. Can you recommend how I can clean my fountain and eliminate the algae? I have tried a white vinegar solution, but not really helping. I am not sure if you are a question and answer guy, but I could use the advise.
    My email is .....
    Thank you, Wendy

  • #2

    Hewitt Berrien (Tuesday, 06 April 2021 00:44)

    Pair of basalt columns ~30”x ~14” polished on top and one flat side, a water feature, now 3 yrs old and showing stains, blotching, etc. Can a regular guy refinish or be done pro?

  • #3

    Mark Ortiz (Tuesday, 06 April 2021 17:54)

    Hello Hewitt. Clean the polished and honed smooth sides with Barkeepers Friend cleaner and white scrub pads. This will remove all the surface contaminants without removing the polish. If you need some shine, wipe on some carnauba wax. Let me know if you need more assistance. Mark

  • #4

    Eric Gieszl (Wednesday, 19 May 2021 01:39)

    When you refer to Barkeepers Friend are you talking about the powder cleaner that you use on stainless steel or the product that I just discovered they make for stone surfaces?

    Will this remove water spot stains from a bathroom floor with black basalt?

  • #5

    Mark (Wednesday, 19 May 2021 22:06)

    Hello Eric,

    I am referring to Barkeepers powder and I have not heard of Barkeepers for stone. I’ll look into that and see what its all about.

    Water spots on Basalt flooring turns either dark or light. Dark spots are soapy or oily in nature and will most likely be permanent and noticeable until the basalt ages and darkens from normal wear and cleaning. White spots or light spots could mean a soap is removing the sealer or soiling “stripping” away the sealer or soiling. Either way only scrub with a green scrub pad to hopefully blend or remove. Remember, basalt does best when it ages over time. Email me a picture and maybe i can help you more.

    Good question.


  • #6

    Mark (Wednesday, 19 May 2021 22:10)


    I looked into the Barkeepers stone cleaner. It is the same as the rest of other stone cleaners. It’s a neutral ph soap, non rinse. Don’t change your cleaner for your counters if you like the one you are using. It may not be recommended for floors because it has a polish in it. Polish additives usually are slippery.

  • #7

    Melinda (Tuesday, 25 May 2021 13:20)

    We just had a dining room fireplace installed and used Jeffrey Court basalt herringbone mosaic tiles on the surrounding sides. The tiles have not been sealed or enhanced. Is it necessary to do so on wall applications? We love the shade of gray that the tiles have and are hesitant to have them darken. Also, the trim pieces are labeled honed so will the sealant act differently on the trim than on the mosaic?

  • #8

    Mark (Tuesday, 25 May 2021 22:32)

    If you expect anything oily or soapy to come in contact with the stone for cleaning or normal wear and tear then I would seal it. Use either Tenax Pro Seal or Dry Treat Stain Proof only! Make sure you don’t use anything could darken it. Follow the instructions and you should be fine. If you think there is nothing that is wet or oily coming in contact with the stone, then leave it alone. Hope this helps. Mark

  • #9

    Debra (Sunday, 13 June 2021 10:02)

    We have an etched basalt fireplace. During our current remodel it has become stained looks yellowish. We had a T&G ceiling installed & also floated tile floors (a lot of moisture in the house during this process). Not sure what caused it but there is staining & it looks very blotchy allover. What can we do to remove the stain & improve the look? Thanks, Debra

  • #10

    Mark Ortiz (Monday, 14 June 2021 09:02)

    HI Debra,

    Etching is not a common characteristic on Basalt. Etching usually occurs with acidic based liquids pitting “etching” the surface causing the reflection to appear different. For starters just scrub with a cleaner such as diluted simple green and a stiff nylon scrub brush. Do the whole hearth the same. Let dry for about 10 minutes. The next step if the yellow is mineral in nature, you can use a mix of bleach and water. Start with 75% water 25% bleach and let it set for about 30 seconds then scrub with nylon brush, rinse and dry.

  • #11

    Lynda Moses (Tuesday, 24 August 2021 17:54)

    I have a water stain on my Basaltina counter. How can I safely remove the stain?

  • #12

    Lauren (Thursday, 02 September 2021 13:05)

    I'm considering using basalt as a bathroom double vanity top. I do not mind it darkening, in fact I would love the stone to be generally darker, more like how soapstone looks after waxing/oiling. If I use a color enhancing sealant, would it face further staining or maintenance, or will the stone stay pretty much uniformly dark? We have soapstone kitchen countertops and a white marble island, so I'm fine with imperfections ;)

  • #13

    Mark Ortiz (Thursday, 02 September 2021 13:59)


    If you are familiar with basalt and you really like the color and grain, then I would say yes! Definitely enhancer or darken if for the reasons you are aware of.
    Also place coasters or napkins under the soap dispensers to prevent rings or spots. My customers that enhance the tops and follow simple instructions have excellent success with basalt. If you have a messy roommate....go with soapstone. Haha.

  • #14

    Lauren (Monday, 06 September 2021 15:28)

    Thank you for this great information! For clarification, we may still get rings and spots after enhancing and using a topical sealer? Blemishes are totally ok and add character, but I also don't want a high maintenance surface. Again, many thanks!

  • #15

    George S. (Monday, 01 November 2021 22:04)

    What would you recommend to darken Basalt flooring that is blotchy and has whitish stains due to hard water. Nothing seems to clean the white stains, so I am thinking the darker the better. Can a dark tint be added to the color enhancers you recommend?

  • #16

    Mark Ortiz (Wednesday, 03 November 2021 17:12)

    George S.

    If you are sure it is hard water deposits, you can try a mild acid cleaner. Start with vinegar first. If it removes it and you like it then leave it as it is. You can bump up the acid with a diluted CLR (start with 1 part acid to 10 parts water and work your way up.)

    The only 'tint' I would try is Uni-black mixed in with Hydrex. Both are made by TENAX. I'm sure there are other types but this is the one I have tested many times and the stain is compatible. Start with a 12 oz. plastic spray bottle filled half way. Add a little Uniblack to it. A teaspoon maybe. Then mix and spray on. Wipe in with a microfiber rag. This is a very scary procedure because it darkens right away and you may need to do it several times or add a little more Uniblack. If you are not confident with your staining abilities then maybe you shouldn't move forward. If you don't mind it being really dark, then keep going, you can't go wrong. You can email me at info@perfectgranitesolutions with photos and more tips.