Andromeda White, Crazy Horse, Namibian Gold, and Black Galaxy—all are names of colorful granite ranging from white to black and everything in between. Isn’t it a bit amazing how variegated the colors of a single type of stone can be? If you ever asked yourself how granite can be so diverse, you’re not the only one! Turns out that the colors of granite can tell us a lot about its origins.
Today is the day to brush off your geology tools because we are going to learn why granite colors range from white to black.
What is Granite?
Granite is classified as an intrusive igneous rock. What does that mean? Molten rock that is flowing upwards to the surface never breaks the crust. As the molten rock cools, it becomes the perfect environment for growing crystals.
Over time, the chemical makeup of minerals can create differential lithification. The minerals will form at different rates, too, which will alter how large certain crystals become. In other words, how long it takes for the molten rock to cool is directly proportional to the size of the crystals that grow. That is why granite has grains and patterns of color.
Furthermore, the fact that granite is formed without getting exposed to oxygen makes it different from extrusive rock. That is what happens when molten rock cools swiftly, creating homogeneity.
Why Granite Colors Range From White to Black
There are literally over 3,000 colors of granite varieties to choose from, though some are rarer than others. But why does granite range in color so much? Why are there so many variances? And why can one chunk of granite create so many unique slabs? As we mentioned earlier, granite is composed of rocks and minerals. The minerals generally range between 20-60% quartz, 5-15% mica (muscovite and biotite), and 10-65% feldspar, though there may also be amphiboles and other trace minerals involved.
The determining factor between granite and another similar igneous stone is the amount of quartz involved. In order for a stone to be called granite, it must have at least 20% quartz.
The colors that develop within a slab of granite are caused by the minerals at the point of origin. For instance, if the molten rock contained quartz, you might get white veining through the rock.
Here are some of the minerals that give granite color:
- Quartz: Lends white and off-white to granite.
- Potassium feldspar: Presented as pink or red, depending on quantity.
- Feldspar: Generally off-white.
- Muscovite: Provides yellow and gold coloring.
- Biotite: Dark brown and black hues.
- Amphibole: Lends dark greens and black to granite.
- Monzonite and anorthosite: These are igneous rocks that contain feldspar, including blue labradorite and small amounts of quartz. Interestingly, these rocks are often called blue granite, though they are not technically granite at all.
Now that you know about some of the minerals creating colors in granite, it’s time to get a better understanding of how each popular granite color is made.
Quartz and feldspar are the two main components of white granite. Quartz is milkier, whereas feldspar is softer—more of an eggshell white. When you see black or red specks in white granite, it is often from amphiboles and potassium feldspar. When the cooling process happens too quickly or there aren’t enough chemicals, the amphiboles cannot form properly and become black flecks.
If you see a rock that is pure white and without any speckling, it is most certainly not granite. In that case, you might be looking at an engineered quartz countertop.
Some examples of white granite include:
- Bianco Antico
- Moon White
- River White
- Andromeda White
The pinkish color you see in this kind of granite comes from potassium feldspar. There might be speckling, too. Whitish coloring is from feldspar and quartz. The dark dotting is amphibole.
Morning Rose is a pink or rose-toned granite that has lighter variances of potassium feldspar and more quartz. If you are looking for a more orange base, Northern Mahogany has a base of brown, tan, and gray with streaks of pinkish-orange.
When potassium feldspar dominates the composition of the granite, it won’t be salmon pink but a deep brick red. Sometimes, red also comes from hematite, which contains iron oxide. A common red granite is Colonial Rose, which has speckles of white, gray, black, and red dispersed throughout the stone. India Red and Twilight Red are examples of deeper tones.
Although this stone is often advertised as green granite—and has properties of granite—most of the time you are receiving marble with serpentine or green soapstone. While green varieties of granite are considerably rare, there are some that contain a rare form of feldspar known as amazonite. Peacock granite is one example of this.
Gold and Brown Granite
Want a more earthy or warm tone in your home? Brown or gold granite is a fabulous choice. There is also a wide spectrum of browns, tans, and golds to choose from, so you can easily find granite that complements the other furnishings in your home. Brown and gold granite often contain large amounts of black, red, and burnt orange, which can come from the presence of amphiboles and feldspar, while mica gives golden granite its more metallic look.
- Caravelas Gold
- Baltic Brown
- Crema Bordeaux
- Almond Gold
When blue granite is advertised, keep in mind that the “granite” part is being used loosely. Almost no quartz exists in blue granite, so it’s not technically granite. There are many potential rocks to consider, two of which we already talked about (monzonite and anorthosite). That said, blue granite has similar properties to real granite, so you can use it for your countertops and backsplashes with no issues.
A few examples include:
- Amadeus Granite
- Blue Pearl
- Brass Blue
Yes, black granite does exist. Take a look at Desert Dream or Black Galaxy granite. However, when you see an absolutely black countertop, it’s probably not granite. Black granite is going to have veining or speckling, as seen with all granite. All black stone is called gabbro, an intrusive igneous rock that contains olivine, amphibole, plagioclase, and pyroxene.
What about black and white granite? Commonly used for countertops, black and white granite is made of equal parts amphibole, quartz, and feldspar.
Looking For Granite Countertops?
Why does granite range from white to black? Because of the minerals present at the time of formation. Since the earth’s crust is so varied, it makes sense that differing amounts of minerals and stones can develop in such unique ways. This also means you have thousands of options to choose from when buying granite for your home.
Let Marble Concepts help! Our specialized team can assist you with finding the perfect granite for your home, as well as craft, install, and maintain your stone counters, floors, accent walls, and more. Give us a call today to learn more.