Natural stone is a versatile material that can be used in many places throughout the home. Commonly used for kitchen countertops, stone is also a great choice for fireplaces, bathroom vanities, cladding, flooring, outdoor kitchens, and fire pits. Choosing the stone best suited to your project means you will enjoy your stone for many years. Spending some time considering your stone choice will allow you to select the stone that works best. Below we consider some factors to take into account, plus some common applications for the most popular stone choices.
Granite is an extremely hard, durable stone that is available in almost any color imaginable. Consistently popular as a low maintenance, high performance kitchen countertop material, it requires little aftercare if it is cleaned after use. Cleaning is simple with mild dish soap and water. In many cases, granite should be sealed using a quality sealer. Once properly sealed, granite will be even more resistant to everyday dirt and spills. Due to its durable nature, granite is suitable for many other applications, such as flooring, shower walls, fire pits, wall cladding, bathroom vanities, desks and tables.
Marble is an elegant, classic choice popular throughout the ages. While white marble is the most popular color choice, many other color options do exist. Marble is softer than granite, so it will stain, etch and scratch more easily. Commonly used for bathroom vanities, backsplashes, fireplaces and bar-top designs, it can also be used for kitchen countertops, but users need to be aware it will develop a patina a slight change in color or texture as it’s exposed to various elements over time as it wears with use. For this reason, it is not usually recommended for high-traffic kitchens.
Quartzite is most often found in white and grey color
varieties, and can look similar in appearance to marble, but is harder than marble, making it an attractive alternative for kitchen countertops. Other popular applications include walls, flooring, and stair steps. Quartzite usually needs to be sealed when it’s installed, to help it resist stains. It should be cleaned regularly with a damp cloth and mild soap and any spills should be wiped up immediately.
Soapstone is a durable stone that is softer than granite and primarily composed of talc. Most commonly found in light grey hues, it can also have tones of blue or green. It is heat resistant, which makes it ideal for fireplaces. Soapstone lining in a fireplace can quickly absorb heat and remain warm for some time after the fire is out. It can also be used for kitchen countertops. Scratches can be easily repaired with ordinary sandpaper and mineral oil. Due to its non-porous nature and resistance to extreme temperatures, soapstone is a popular choice for outdoor kitchens.
soapstone. Photo courtesy European Stone Concepts.
Onyx is easily identified due to its striking appearance, with alternating bands of color. It is most commonly used as a statement piece, and is often backlit, such as on bar-tops or a statement wall. It can also be used as a backsplash for kitchens and bathrooms, but is not usually recommended for countertops or high traffic areas due to its delicate nature. Onyx is a fragile stone that needs to be cared for to prevent scratching and etching. If it is used for countertops, it needs to be sealed properly and then cleaned with special stone cleaner at frequent intervals to help prevent scratching and staining.
Green onyx from Pacific Shore Stones. Photo courtesy of Ellen Cornell, Cornell & Company.In simplified terms, you can think of gneiss as a metamorphic version of granite. Both gneiss and granite are made of feldspars, quartz, mica, and smaller amounts of dark colored minerals like hornblende. Both have tightly interlocking minerals, so they are minimally porous. On paper, they have similar properties and can be used in the same ways.
The difference between granite and gneiss is in their overall texture and movement. Granite is evenly speckled. It formed from liquid magma that cooled and crystallized. Granite is like rocky road ice cream a solidified conglomeration of different ingredients.
Gneiss, arguably, is more visually interesting. It’s characterized by stripes, linear bands, or flowy rivers of color. This pattern is called foliation and it’s a result of the rock being squeezed and heated. Gneiss is like ribbon candy
– it’s been folded and swirled while hot, and then left to harden. The stone captures the expressiveness and movement that come from its dynamic origins.
The striped, wavy look of gneiss comes from extreme amounts of compression. The random orientation of minerals you see in granite is an inefficient use of space, sort of like the ragtag pile of magazines you left next to the couch. Those magazines take up less space if you stack them all the same way, right? This principle applies to minerals too. They align themselves in the same direction when they get buried a few miles deep and pressed between colliding continents.
If the pressure on the stone is evenly distributed, you get straight or gently flowing stripes, like Agatha Black or Viscount White. If the compression involves folding or twisting, as it often does in geologic crumple zones, then you get a stone with wavy or ribbonlike texture. Amadeus and Black Forest are examples of gneisses with dynamic textures.
Just like you and me, gneiss comes from its parents
All metamorphic rocks have a parent rock, which is a rather sweet way of describing what the stone was before it encountered the heat and pressure that transformed it into a metamorphic rock. The parent rock of gneiss can be granite, but it can also be shale or an impure sandstone meaning it contains more than just pure quartz sand.
Previous articles have described the continuum of metamorphism as a stone is exposed to increasingly torturous heating and compression. Shale becomes slate, then phyllite, then schist, then gneiss. Each of these steps is gradual, as the stone slowly changes in response to the conditions it experiences.
Regardless of its geologic parent rock, gneiss is near the end of the metamorphic road. Heat it further and it begins to melt. When it starts to melt, it doesn’t do so at once. The mineral quartz will melt first. Another delicious food analogy applies here. The beginning of the melting process is just like a chocolate chip cookie left in a warm car. The chocolate chips will melt long before the rest of the cookie does. In gneiss, you can often see fluid-looking pockets of quartz that were melted while the rest of the rock remained solid. A gneiss that was partway melted is called migmatite, which means mixed rock. Part metamorphic, part igneous. Examples of migmatite are Titanium, Cosmic Black, and Tropical Black.
The geologic basement
Gneiss is one of the most common rocks on Earth’s surface. It forms the basement rocks that are below most land masses. These basement rocks are over a billion years old and, just like the basement of your house, they are the foundation for the layers above. Newer stones pile up on top of the basement. But sometimes those newer layers get scraped away by erosion, and the older layers get heaved upward by mountain building. Behold, the basement sticks out at the surface. I like how gneiss offers a glimpse of what went on in the depths of Earth’s crust; the flowing swirls of color reveal how the whole rock was once fluid and bendable.
One of the fun things about natural stone is the huge range of aesthetics that are expressed in stone. Gneiss is no exception; it comes in many variations, and can appeal to many different styles and tastes. While all gneiss is striped or banded, the bands can be straight, gently wavy, or chaotic. The colors can be mostly dark, or mostly light. The stone can be black and white, or black and pink, or black and gold, or nearly any combination thereof. Interesting minerals like garnets dark pink, round specks or kyanite blue, elongated crystals can liven up the usual combo of minerals.
Note that a stone of a given name can have different patterns depending on which direction it is cut and which part of the quarry it is from. Viscount White, for example, can be serene or vivid. When shopping for gneiss, it’s helpful to select specific slabs to get the look you want.
Uses of gneiss
Gneiss is a terrific stone for many purposes. It tends to be blocky and dense, and makes robust dimension stone for buildings, walls, and landscaping. Gneiss is also a durable choice for interior uses, and makes a fantastic countertop or tile. The minerals in gneiss do not etch when exposed to normal household acids like vinegar or citrus. Take comfort in knowing that gneiss can withstand heavy use; it is made up of minerals in the 6-7 range on Mohs scale, meaning it’s harder than glass and about the same hardness as steel. It tends to be low in porosity, meaning it is not likely to stain, but there is some variability here, and some gneisses benefit from sealing.
There are two caveats when working with gneiss. One is that the linear grain in the stone can sometimes mean that the stone wants to split along those layers. This is not common, but worth considering if you have a large overhang. Try to minimize overhanging areas where the overhang is parallel with the natural grain of the stone. Or, if you do use the stone this way, be sure it’s well-supported underneath.
Second, keep an eye out for large areas of mica minerals, which are readily identified by their glittery look. In gneiss, mica minerals tend to form their own layers, which are likely weaker areas than the surrounding feldspar and quartz. Some of the dark colored gneisses have large amounts of biotite mica. Learn more in the article about schist.
All in all, gneiss is a durable, functional stone with a pleasing range of aesthetics. If you crave a rock-solid building stone or a countertop with flow and personality, check out a nice piece of gneiss.
Choosing natural stone instead of a manmade product means that your design will be truly unique, because each slab of natural stone is different. When choosing your stone, be sure to visit stone yards to look at the actual slabs you’re going to use, rather than selecting from a sample. This allows you to see the color, veining, and movement that appears throughout the slab. Natural stone presents a huge range of color choices, so taking samples of other parts of your project, such as paint samples, cabinet doors, backsplash tiles, or faucets, can help narrow down the selection.
It’s important to think about the space where the stone will be used. If it’s for a high-traffic area, such as a busy family kitchen, you may want to select a harder stone that is more resistant to abrasions. Softer stones require more frequent cleaning and care to prevent etching and scratching. For this reason, softer stones are often more suited to areas where the stone is not exposed to as much use, such as wall cladding, backsplashes and bathroom vanity tops. The amount of time you want to spend cleaning and caring for your stone should be considered as part of the selection process.
Commonly Used Stone Types
Using natural stone for a project presents an exciting array of choices. Ultimately, the choice of stone is down to personal preference, but the factors discussed above should be taken into consideration to help with the decision making process. Talking to an experienced stone professional about your vision and specific needs for your project is also recommended. For more information about caring for stone.