Understanding Stone Types:

Natural stone is rapidly making its way into the showrooms of most new development sales offices. With this popularity, we’ve seen an increase of calls from homeowners who were not properly informed on the differences between stone types, or what to expect with regards to durability and long term maintenance.

There are a multitude of stone types, they are categorized by how they were formed, and their mineral composition. We will not be making a geological analysis of the multitude of stone types, instead, this post aims to simplify these many families into more generalized groups based on their maintenance attributes. For each family we will give a brief description of the following : stone use, hardness of the material (scratch resistance), their susceptibility to etching (acid resistance), porosity (sealing schedule), and ease of repair.

Marble, Limestone & Travertine

Marble blog 3

Brief: Why group these materials together? The rate of servicing, susceptibility to etching and ease of repair is all very similar between these materials due to their mineral composition and hardness. Keep in mind they are not alike with regards to density and appearance, mainly due to how they are formed (metamorphic vs. sedimentary). Marble and limestone are quickly becoming very common materials for kitchen countertops, but have long been used in baths or as a floor surface. Many people find marble and limestone much warmer aesthetically when compared to granite. Marble is much more elegant than travertine due to its unique patterning and lower rate of imperfections, being a metamorphic stone, marble is much denser/finer grained than most limestone and travertine, making it an excellent candidate for natural high gloss finishes. Prices vary when it comes to buying marble and limestone, but generally speaking travertine is the most budget friendly of this group. As a side note, since travertine is so often filled with imperfections, it wears very well over time, making etching and traffic patterns very difficult to notice, I would consider this the most maintenance free material if you appreciate it’s natural variations.

Susceptibility to Etching: 10

These materials are all similar in their mineral composition, and very reactive to acids, they will etch easily.

Hardness: 3-5 (Mohs scale):

Since marble is mainly composed of calcite, it is rated at a hardness of around 3-5 mohs. For this reason we usually recommend having a good carpet to collect outside dirt and grit, and regularly dust-mopping to remove any grit brought in from the outdoors. Outdoor sediment is rated at around 6-7 mohs, which will easily scratch and wear away at these calcite based materials.

Porosity:

Like granite, it is hard to determine how porous your particular material may be, however unlike granite, all marble/limestone/travertine surfaces are porous. As a general rule, marble and travertine are less porous than limestone. Often these materials require on site sealing post installation, even if they are advertised as already sealed. High traffic areas with regular exposure to moisture and steam (showers, baths, pools etc.) will require sealing more frequently.

Repairability: 10/10

These calcite based materials are a pleasure to work with due to their softness and predictable grain patterning. We can with relative ease isolate a damaged area for repair and match it’s surrounding finish. Unlike granite, it is much easier to transform these materials from a polished finish to a honed finish, or anywhere in-between.

Granite:

natural stone

Brief: Granite is ubiquitous with luxury counter tops, until the last decade or so, it was very rare to see marble or specialty materials (ceasar stone, onyx, epoxy etc) installed in a kitchen. Due to it’s incredible hardness as well as affordable cost (roughly 25% cheaper than marble) it’s no surprise that granite continues to dominate as a reliable countertop material. From an aesthetic perspective, it is not uncommon for granite to be referred to as a “cold” material, I suspect this is why it is rarely used as a floor tile in residences. While most granite is very consistent, showing little variation in colour or patterning, veined varieties do exist. A veined granite will generally appear closer to a marble or quartzite, appearing “warmer” while remaining durable, impervious to etching, and not particularly porous. While veined granite is beautiful, it is much rarer and thus significantly more expensive than regular granite, of course, it will need much less maintenance than marble, so long term savings should be considered.

Hardness: 6-7 (Mohs scale):

Granite is roughly twice as scratch resistant when compared to marble. It is unmatched as an exterior building material due to it being very dense, and nearly impermeable.

Susceptiblity to Etching:

Simply put, granite DOES NOT ETCH. The mineral composition of granite is mainly quartz and feldspar, neither of which react to acids.

Porosity:

Generally speaking, granite is one of the least porous materials we encounter, but this is not always true. In our experience, lighter granites are more porous than darker (denser) granites, and it is not uncommon for clients with absolute black granite counters never using sealer, while lighter granites may quickly show signs of absorption if left unsealed. To check for yourself, let a moist sponge or paper towel (clean water) sit on your stone for a few minutes, then look for signs of absorption (darkness).

Repairability: 6/10

Being so durable and resistant to staining, granite rarely needs servicing beyond silicone replacement and sealing. At the same time, it’s hardness means any grinding or resurfacing will be significantly more labour intensive when compared to marble. For example, an equally worn marble floor would take anywhere from ¼ to ½ the amount of effort to re-surface when compared to granite. Simply put, granite repairs are not often needed, but when they are, they are expensive.

Natural Quartz

quartzite blog c

Brief: Natural quartz (not to be mistaken with quartz aggregate material such as caesar stone) has become more and more popular over the last few years. We do not consider it a ‘mainstream’ product due to cost, and it is rarely encountered outside of custom applications. Aesthetically, I consider some natural quartz the epitome of beauty in a slab of stone. Quartz slabs often exhibit a subtle transparency, filled with beautiful crystalline veins, and often with very consistent colouring.  The main downfall of quartz is there is no sure way to know if it will etch, we’ve encountered quartz counters that were impervious to etching and others that would respond to acid like your average marble. There are many resources/testimonials available online, we recommend thorough research and to test your slab to be certain it is etch resistant if that is your aim. Take time to express these concerns to your supplier before purchasing slabs. Our research suggests darker slabs of quartz to be less prone to etching than lighter slabs.

Susceptibility to Etching: (read above)

Hardness: 7 (Mohs scale):

Quartz is consistently gauged to be as hard or slightly harder and more resistant to scratching than granite. Like onyx, if a slab is prone to etching, etched areas will likely be less scratch resistant due to weathering.

Porosity:

Like granite, quartz porosity will vary slab to slab. Generally speaking, quartz is much less porous than marble/limestone, but still requires sealing. Quartz is much less prone to the discolouration seen in poorly maintained marble, but deposits of minerals within the quartz can still cause discolouration if not properly maintained.

Repairability: 5/10

Quartz is often on par with granite when it comes to repairs, however it has some unpredictable qualities. Quartz often has deposits of other minerals which do not polish to the same lustre as the rest of the slab, the physical pressure applied during original manufacturing cannot be replicated on site, making matching the original luster difficult in some slabs. To date we’ve managed to always match the finish, but are aware of this limitation and feel it is worth mentioning. Due to the transparent nature of quartz, clear epoxies with longer curing times may be necessary, adding time/cost to chip and crack repairs.

Onyx

onyx blog

Brief: Onyx is a dramatic, translucent material that has always been used for it’s unique patterning (banding) and dynamic colouration. We usually see this material used as furniture tops and powder room/bath counter tops. Onyx is on par with marble with regards to maintenance needs, which is why we rarely see it used in kitchens or as a floor tile in high traffic areas. Onyx looks best polished to a high gloss finish, as this reveals is transparency, unfortunately this means there is no low maintenance solution if you choose to use it in a vulnerable area of your home. Due to the transparency of onyx, it is a prime candidate for backlit applications, including countertop islands, reception tops, or as a unique wall covering. Back lighting will accentuate the fine concentric layers of mineral deposits (banding) within the stone and reveal its depth. Expect this material to cost more than your average slab of crema marfil (marble).

Susceptibility to Etching: 10

Onyx is very reactive to acids, it will etch easily.

Hardness: 6-7 (Mohs scale):

Onyx is rated as being as hard as granite. While it may be hard like granite, it is still very susceptible to etching and softening due to introduction of acids, this is called weathering. For example, an onyx floor that has been washed with vinegar or other acidic cleaners will be easier to scratch than in it’s polished (un-weathered) form.

Porosity:

Onyx is considered a porous material, and should be treated the same as marble with regards to your sealing schedule.

Repairability: 8/10

The tools and compounds used to polish marble are also used with onyx, and the material itself responds very well. Due to its hardness, some extra smoothing techniques are required to bring it to a full gloss polish. Because the material is translucent, clear epoxies with longer curing times may be needed to repair chips or cracks, this can also add to cost.

Soapstone

soapstone blog

Brief: Soapstone is currently trending south of the border for its unique rustic look and resistance to etching. Soapstone is naturally non-porous and requires little professional maintenance if any at all if this rustic material suits your aesthetic preferences. If you are looking for a high gloss polished counter, or a scratch resistant surface, we suggest avoiding soapstone. When choosing this material it is very important to know the specific hardness based on where it originated, as soapstone softness can vary drastically region to region.

Susceptibility to Etching: 0

Similar to slate, the material itself will not etch, but spills that react with applied mineral oil or wax may appear lighter than the surrounding stone, imitating an etch. Re-application of mineral oil/wax should hide the discolouration.

Hardness: 1-5

Soapstone is made primarily of talc, making some variants incredibly susceptible to scratching, it is important to work with your stone supplier when choosing a slab to ensure it performs to your expectations.

Porosity: 1/10

Soapstone is a non-porous material by nature, it will not require any professional sealing beyond the use of mineral oil or wax if preferred for aesthetic reasons. Application of oil or wax is not required, but will darken the stone naturally and is recoatable if an area becomes worn or damaged.

Repairability: 7/10

Soapstone is very soft, and thus easy to grind and resurface and is generally left with a patina finish. Because the minerals in soapstone do not react well with traditional marble polishing compounds, all re-surfacing must be performed mechanically (no chemical assistance) which can add to cost. If the soapstone is being maintained with mineral oil, re-application of the oil often hides the “chalkiness” caused by scratches. Homeowners who pick soapstone are generally more inclined to maintain their counters themselves, as mineral oil application is required more often than sealing is required on a marble counter. Most cases where etching is described are not actual etching, rather a reaction between the “etch causing product” and the mineral oil or wax, reapplication of the oil/wax should restore the area to its dark tone.

Slate

slate blog

Brief: Slate is the only material mentioned that is not a candidate for resurfacing. The surface of a slate tile is it’s natural finish, which consists of a subtle rough but generally consistent texturing. Because it is relatively soft compared to even marble, slate is often coated with topical finishes to protect it from turning chalky and scratched. Over time this floor finish may fail or collect dirt at which point it can be stripped and sealed with a colour enhancer or even a clear penetrating sealer, in most cases we recommend non-topical coatings. The recommended method of sealing depends on the location of the material, traffic, and desired appearance.

Susceptibility to Etching: 0

Slate does not etch, but topical coatings generally found on slate may react to solvents or other chemicals, lightening the area and looking similar to an etch.

Hardness: 3-4 (Mohs scale):

Slate is quite soft, and will display scratching and wear relatively quickly when exposed to the elements. This isn’t necessarily bad, as it does wear consistently if a rustic appearance is desired.

Porosity:

Slate is not particularly porous, but this varies from where it is sourced. Since slate does absorb sealer readily (both clear and colour enhanced penetrating sealers) it is safe to assume oil and other contaminants will quickly penetrate into most raw slate surfaces. If a topical coating is applied sealing is not needed as often, but once dirt has penetrated into the topical finish or discolouration occurs, stripping the floor finish is required before new sealer can be applied.

Repairability: 2/10

Since slate tile is generally left in it’s raw form, resurfacing is not possible. Scratched or high points cannot be removed without making the affected area look drastically different from the original finish. Most of our slate repairs consist of stripping topical coatings and either applying a penetrating sealer (both clear or colour enhanced) or re-applying a thin layer of topical coating if the customer prefers a glossier finish. Chips and cracks can be repaired with a colour matched epoxy, but again will not match the natural finish.