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.


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Comments: 1
  • #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