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A Soft Spot for Soapstone

by | Oct 12, 2018 | Educate, Geology Series |

While browsing the slab yard or showroom, each type of stone seems to possess a distinct personality. Glossy, polished granite is the crisp tailored suit, while marble is like flowing linen—a little wrinkled but always in style. And soapstone? Without a doubt, it’s the flannel shirt of natural stone. Soft, touchable, and always comfortable. You can’t even walk by a slab of soapstone without stopping to pet it.

Soapstone enjoys a cult-like fan base: I love the organic-ness of it, writes one devotee on Houzz. But it’s not for everyone. I find these photos rather sobering, laments another commenter after viewing images of the patina that soapstone can acquire.


Yes, Soapstone is Soft

“All stones have benefits and disadvantages,” says Anthony Lacour of M. Teixeira. “There’s no such thing as a perfect surface.”

As the branch manager at M. Teixeira’s Denver office, Lacour has been working with this iconic stone for a dozen years. He suggests the best way to get a feel for soapstone’s hardness is to experience it personally. “Let people test for themselves,” he says.

Hardness of most commercial soapstones ranges from 1 to 4, but Lacour has found that the exact Mohs number is not as important as just getting a sense for it. “Use a fingernail and a key as your hardness indicators,” he advises.

Soapstone’s softness might be a dealbreaker for some—it comes down to knowing yourself and recognizing if a scratch in the stone is going to ruin your day, or how long it will take you to forgive a family member who accidentally drops a frying pan on the countertop.

Lacour explains the upside: “The good thing is that you can fix it yourself.”

A fresh coat of mineral oil will render small scratches invisible. Larger marks can be removed with sandpaper. Lacour recommends 120-220 grit for most scratches; if you prefer a shinier finish, you can follow up with 400-500 grit. Then re-oil the surface to restore the luster, and you’re all set.

Even a gouge is fixable—it can be filled with a mixture of stone chips and epoxy. This can be tackled by a professional or by a seasoned DIYer.

Steve Schrenk is the digital media director for Polycor, and he has worked with stone as a sculptor, fabricator, and designer. He describes soapstone as “very user friendly for self-repair,” noting that soapstone appeals to the type of person who “likes to roll up their sleeves and do it themselves.”

A Houzz commenter sums it up best, What I love love love the most about soapstone: If you are a DIYer at heart (or a control freak, like I am), then the self-maintenance of the counter is just wonderful.”


And Now for the Good News: Soapstone’s Superpowers

Once you’ve come to terms with soapstone’s softness, you can revel in its strengths. By and large, the stone is remarkably resistant to staining or damage from acids. The density of the stone makes it practically impervious. That smoldering casserole you left in the oven while binge-watching Better Call Saul? Put that right there on the stone, thank you very much.

These superpowers were not bestowed on soapstone by any magical process. It comes down to the properties of the minerals in soapstone. Soapstone’s primary ingredient, talc, is chemically inert, which is why soapstone is generally unaffected by acids and alkalines. Talc is also hydrophobic, meaning it quite literally repels water.

The mineral magnesite is another major component of soapstone, and it has the ability to retain heat. The properties of magnesite allow soapstone to work so well as an insulator or a fireplace. The stone is capable of absorbing heat and then slowly radiating it off, providing the long, sustained warmth so appreciated in cold climates. Lastly, soapstone is a dense arrangement of small minerals, with minimal pore space that might allow water to seep in. Low porosity means that soapstone will not absorb liquids nor harbor bacteria—a perk for the germaphobes among us.

Schrenk sums up the yin and yang of soapstone: “People tend to latch on to the scratching aspect of soapstone,” he says. But they may be “missing out on some of the other aspects of the stone” that make it so appealing.


Soapstone’s Quirky Geology

Soapstone is an unusual type of metamorphic rock. Most metamorphic rocks are heated and squished versions of their former selves. Limestone becomes marble. Sandstone turns to quartzite. But soapstone doesn’t abide that simple recipe. Soapstone comes about from a series of chemical reactions that take place deep underground. Hot groundwater carries dissolved minerals from one rock to another, allowing a mingling of ingredients that begets entirely new minerals. In some cases, soapstone is a derivative of dolomite or dolomitic marble (like Super White). In others, soapstone comes from ultra-deep, ultra-dense rocks from Earth’s mantle. In this latter case, serpentine is also formed, and hence, soapstone and serpentine can often be found side-by-side in a quarry or outcrop.

Soapstone’s signature soapiness comes from the mineral talc. Talc is a member of the mica family, and is made up of thin flakes. The flakes are held together by a very weak type of bond, which allows the layers to easily slide against each other, giving the stone a slippery feel.

Talc is the softest mineral on Earth, with a hardness value of 1. Soapstone always contains some talc, but the amount varies, and therefore so does the overall hardness of soapstone. Stones with high talc content are called steatite, and are useful for carving. Commercial soapstone slabs generally have 30% to 50% talc, with the remainder of the stone being chlorite, magnesite, amphibole, and other minerals. In general, the lower the talc content, the greater the hardness.

Geologically, soapstone is a family of stones rather than one specific thing. There’s broad variation in the types of minerals present and their proportions. This is all the more reason to thoroughly investigate potential stones and to work with reputable dealers and fabricators.

If a stone looks sort of like soapstone but can’t be easily scratched with a pocketknife, it’s likely serpentine rather than soapstone. Virginia Mist and Jet Mist are granites that resemble soapstones, but are much harder. When in doubt, use the diagram below and read up on how to tell green stones apart.


Evaluating the Hardness of Various Soapstones

Soapstone really is different from most other types of stone. What better way to explore this than to try a battery of tests and see how it performs. M. Teixeira sells a sample kit of various soapstones to allow customers to experience a range of soapstone colors, textures, and hardnesses. I used a set of Mohs hardness picks to get up close and personal with the hardness of 12 soapstones. I tried to scratch different minerals in the stone with picks of various hardness values. I also used my fingernail and a pocketknife so that I could compare common items with Mohs numbers.

The results varied depending on how much talc the stone contained and what other minerals were present. While all the samples fell into a range between 1 and 4, they were different from one another, and even a single stone could have different hardness values in different places.

A summary of soapstone hardness is given in the table below, and the stones are arranged roughly from softer to harder.


Testing Acid Resistance

After I checked out the hardness of the 12 soapstones, I moved on to acid tests. I put a 10% solution of hydrochloric acid on every sample, and also used standard white vinegar to check for etching. I left the acids there for at least a half hour, before scrubbing the stones with soap and water and inspecting them for damage.

Several stones had a slight bubbling reaction with hydrochloric acid. This is expected because soapstone sometimes has calcite veins, and/or it can contain magnesite, which will have a very subtle reaction to acid. Interestingly though, 11 of the 12 stones showed no damage, etching, or staining from the hydrochloric acid, even though the acid initially looked like it had stained some of the stones. But it washed away and left the stone unaffected. Similarly, vinegar left no mark whatsoever on 11 of the 12 stones.

One stone, Stormy Black, showed a faint etch mark where vinegar was left puddled up for several hours, and the hydrochloric acid left a stippled white pattern on the black stone when left for an hour. This stone appears to be somewhat susceptible to acids, and likely has more magnesite than the other samples. The dark color and fine texture of Stormy Black may also make the changes appear more noticeable.

Aside from that, the other 11 samples looked brand “new” (while appreciating the fact that they are indeed several million years old!).


Oiling or Waxing Enhances the Finish of Soapstone

Soapstone can have two distinct looks, depending on the finish. It can be left untreated and will attain a soft grey color and a matte finish. Or, the surface can be oiled or waxed, which will darken the color and impart a satiny luster. “You get multiple looks from the same stone,” says Lacour.

To oil, or not to oil: that is a frequent dilemma among soapstone owners. Light oil like mineral oil is easy to wipe on but will fade fairly quickly. Wax can also be used as a surface treatment. It requires more effort to apply, but it lasts longer. An oil/wax blend strikes a happy medium between the two.

One needn’t agonize over this decision, because it’s always reversible. Thanks to soapstone’s density, the oil simply sits on the surface. It doesn’t penetrate the stone. If you change your mind and decide you don’t like the oiled look of your soapstone, you can scrub most of it off right away, or simply wait for it to disappear on its own.

One minor caveat to the oiled vs. naked finish is the color of the seams. During installation, the epoxy in the seams will be dyed to match the stone. But since the color of the stone depends on whether it’s oiled or not, you could end up with a slight mismatch. When in doubt, savvy soapstone owners suggest going with a lighter color in the seams, because the seam can be darkened more easily than it can be made lighter.


Best Uses for Soapstone

Around the world, soapstone has been shaped into cooking pots, utensils, vessels, and sculptures for thousands of years. Soapstone’s workability made it especially useful during the Bronze Age, when molds were carved out of soapstone and filled with molten metal.

Today, soapstone is a beloved material for wood stoves and fireplaces. At the Bridger Bowl ski area in frigid Montana, a soapstone stove is the central feature in a slopeside warming hut. The stove is thoughtfully placed in the middle of the room, beckoning to visitors and easing the woes of chilly children. Once heated, the stone gives off warmth long after the fire goes out. Even after sitting idle all night long, the soapstone is still warm the next morning.

Soapstone is well known as a worktop in laboratories, where its chemical inertness and heat resistance allow it to withstand all manner of abuses.

These same traits make soapstone an enviable material in the kitchen, where it’s commonly used for countertops, islands, or sinks. Unlike many types of natural stone, soapstone cannot be polished to a glossy shine. Instead, it has a soft, warm glow and rounded edges that help a space feel comfortable rather than imposing. Our kitchen looks loved! It looks lived in! People who eat together and tell stories and make each other laugh and spill their drinks live here!” writes a fan of soapstone on Houzz.

Both Lacour and Schrenk agree that soapstone fills a distinct niche in the industry. Soapstone’s grey tones and honed finish are on-trend nowadays, but soapstone won’t ever go out of style. While some stones draw attention to themselves, “soapstone’s subtle colors plays well with other elements of design,” explains Schrenk. “It fits a 100 year old building or new construction,” observes Lacour. Schrenk echoes the same sentiment: “It’s modern use of a traditional material.”


Alberene – Virginia’s Soapstone Quarry

Not far from Charlottesville, Virginia sits a large soapstone deposit and an active quarry that dates back to 1883. Over the years, Alberene soapstone was destined for a variety of applications, ranging from industrial uses of talc in tires and roof shingles, to practical objects like sinks, bed warmers, and griddles. Polycor purchased the Alberene quarry 5 years ago, and they’ve been pleasantly surprised by the enduring popularity of soapstone. “It’s surpassed everyone’s expectations,” says Schrenk. Alberene’s most popular soapstone is called Church Hill, literally named because of a hilltop church near the quarry. Nowadays, the quarry mostly produces slabs destined to become countertops, tiles, pavers, treads, wall caps, and fireplace inserts. “There’s a huge surge right now, especially for countertops,” says Schrenk.

The uptick in demand is easy to appreciate. Alberene soapstone is local, natural, and has “a tactile quality” that customers are drawn to, explains Schrenk. He finds that once customers learn what sets soapstone apart from other stones, “they sing its praises.”


Is Soapstone Right for You?

Choosing stone is always a personal decision, but even more so with soapstone. Only you know your situation and squeamishness, and Lacour’s advice to test the stone yourself rings true. Thankfully, soapstone dealers typically provide samples for customers to work with, so you can bring pieces home and try out your own scratching, etching, and staining tests. (You can also take our Stone Personality quiz.)

This bit of online advice nails it: “I’m looking forward to the aging and patina. But it would be sad if someone who wasn’t up for it spent a lot of money and had their heart broken.”

As with every material, the more you learn about it and the better you understand your own needs, the easier it will be to narrow down your choices.

If you’re curious about soapstone, spend some time interacting with it and see what you think. I found myself falling more in love with the samples the more I played with them. Another Houzz commenter said it best: “To those of you considering soapstone, do not be afraid!”


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