Granite has been the gold standard of countertops for a long time (well, until recently anyway). What sets granite apart from other stone countertops for a lot of people is that it’s a natural, highly durable stone, and the fact that there’s an impressive range of colours you can choose from for granite countertops. The latter is what often sparks the most wonder for people. How exactly do they get their colour though?
It all boils down to the mineralogy of each granite piece. Granite is mainly composed of quartz, alkali feldspars, plagioclase feldspars, and other mineral impurities present during its formation. Feldspars in particular are easily affected by weathering and exposure to ground fluids due to their chemical instability, which dramatically alters their appearance (they can even change into completely different forms like clay minerals, bauxite, limonite, etc.). It’s the combination of quartz-to-feldspar makeup, mineral impurities, and weathering effects that produces the variety of colours we see in granite today.
Let’s take a look at some of the common granite colours and their mineral causes:
- Cloudy white (some translucency): Quartz – impurities like amethyst can also tint it a faint purple while radiation can tint it a smoky to black shade
- Dark brown (nearly black): Biotite
- Dark green (nearly black): Amphibole
- Off-white (solid): Plagioclase feldspar – varies from greyish-white, bluish-white, reddish-white, and greenish-white
- Red: Iron oxide from hematite
- Salmon pink: Potassium feldspar
- Yellow or glittery gold: Muscovite
Just for fun, if we apply what we now know of granite colours to actual granite pieces, we can make an educated guess as to what their mineralogy is like:
- Alaska White: Quartz, plagioclase feldspar, biotite
- Crazy Horse: Quartz, plagioclase feldspar, potassium feldspar, biotite
- Crema Bordeaux: Quartz, biotite, iron oxide from hematite
- Minsk Gold: Quartz, amphibole, plagioclase feldspar
- Tan Brown: Quartz, potassium feldspar, iron oxide from hematite, biotite
- Titanium Black: Quartz, biotite, muscovite
- Uba Tuba: Quartz, amphibole, muscovite
Now, this extra knowledge on the origin stories of different granite pieces may not be very useful to people who only care about the final product colour and how it’ll match up with the kitchen design. If you like drilling down even to the microscopic level when designing your dream home though, then the mineral composition of your granite countertop is something else you can have a lot of fun customising.
You can either choose your granite countertop based on your favourite minerals or you can take the whole thing to a metaphysical level. Since ancient times, many different cultures believe that each mineral, gem, or crystal has certain metaphysical and healing properties. For example, biotite is believed to be helpful in staying organised in life while hematite is said to be a protective mineral that revitalises your body through improved oxygen flow in your bloodstream.
The mineralogy of granite may turn out to be an important design consideration for you if you believe in the metaphysical properties of minerals. If it’s not your cup of tea…well, now you have another conversation topic centred around your granite countertop when you have guests over or another random tidbit of information that may come in handy on your next trivia night.