A Guide To The Wonderful World Of Tourmaline
One of my all-time favourite gemstone families is the tourmaline. When you see the sheer variety available in this one group of gemstones, it's hard to find a tourmaline that doesn't sing to you. Tourmaline is a supergroup of minerals found in many locations worldwide, including Brazil, the USA, and many parts of Africa. Suppose colour is a significant factor in choosing a crystal or gemstone. In that case, there will surely be at least one tourmaline that will jump out and grab your attention. It quite literally comes in almost all of the colours of the rainbow.
Tourmaline is a borosilicate mineral with different colours occurring due to the inclusion of other minerals such as iron, copper, aluminium, manganese, lithium, sodium, and magnesium. It is a reasonably durable stone with a rating of 7 to 7.5 on the Mohs scale, the 1 to 10 scale used to determine the hardness of gemstones and minerals. Despite being of a reasonable hardness, tourmaline tends to be somewhat brittle. As such, it is pretty easy to chip and damage the stone. Tourmaline is quite distinctive in its rough state, easily identified by its unique growth pattern of long straight rod-like formations. This growth formation is seen clearly in the image of a large specimen of rough black tourmaline, as seen below.
As seen in the image below, It is common to find tourmaline growing in quartz. Tourmalinated quartz is one such example, with the striking black tourmaline rods growing throughout the clear or white quartz. Green and pink tourmaline are also frequently found growing within the white quartz. Metaphysically speaking, these crystal specimens are a real double threat, as they combine the powerful metaphysical benefits of the tourmaline with the amplifying properties of the clear quartz.
Tourmaline is recognised as the birthstone for those who are born in October. In the early 1700s, the name 'tourmali" was given to coloured stones found by Dutch traders in Ceylon (Sri Lanka). The colourful pebbles were assumed to be zircon. It wasn't until another hundred years or so, in the early 1800s, that they were discovered to be a completely different mineral composition. Throughout its earliest discoveries, the different colours of tourmaline were mistakenly identified as other commonly known gemstones. Green was thought to be emerald, and many deep red coloured rubellite tourmalines have been mistaken for rubies.
Colours:
The colours of the tourmaline are really like no other gemstone. A trained eye will usually see the slight differences in hue that give away a green tourmaline from an emerald, a pink tourmaline from a pink sapphire, and a blue tourmaline from a topaz or aquamarine. And if picking one single, solid colour as your favourite seemed like a daunting task, tourmaline is here to make your choice even harder with its breath-taking bi-coloured and sometimes even tri-coloured varieties. Here we will go a little more in-depth on the many beautiful colours of tourmaline.
Green:
Green tourmaline is one of the more commonly seen colours with hues ranging from deep forest green, olive-toned specimens, light minty green, and even the neon green of the chrome tourmaline. Green tourmaline is sometimes referred to as verdelite, and you may occasionally hear it called elbaite. These names refer to the various mineral groups that form the supergroup of tourmaline. Elbaite tourmaline gets its colour from the inclusion of lithium in its composition. The main difference between the common green tourmaline and the chrome green is the presence of chromium or vanadium in the chrome green tourmaline, which gives the bright, neon effect. Chrome green tourmaline is not from the verdelite or elbaite groups of tourmaline but instead comes from the dravite group and is sometimes referred to as chrome dravite, but not commonly. Referring to tourmaline by their mineral group names quickly becomes confusing, which is why it is almost always just referred to by its colour grouping.
Pink:
Pink tourmaline comes in various shades from light, candy-floss pink through to rich, raspberry reds. The term rubellite is usually reserved for the intense pink/red tourmaline that may have secondary hues of orange or purple. It is the inclusion of manganese that gives pink tourmaline its colour.
Blue:
Blue tourmalines come in a range of colour from deep teal through to bright aqua. The darker, teal-blue tourmalines ( as seen above) are commonly referred to as indicolite. Indicolite tourmaline gets its colour through a complex mix of minerals, including aluminium and iron.
While indicolite is somewhat rare, especially in relation to the greens and pinks, another variety of blue is much rarer and, as such, commands eye-watering prices. Paraiba blue tourmaline ( seen in rough form in the above image) is bright, vibrant, aqua blue in colour due to the inclusion of copper in its composition. Named after the Paraiba locality in Brazil, where it was first discovered, this variety of tourmaline has since been found in a small number of other localities worldwide. No matter the source, only true copper-bearing tourmaline should be referred to as Paraiba. Given the popularity, rarity, and price of this stone, the term "Paraiba" is often, wrongfully, given to other gemstones of similar colouring. These are, most often, man-made or treated to achieve the colour. Using the term "Paraiba" to describe these stones is a way to mislead the consumer into thinking that they are purchasing a stone that is much more valuable than it actually is. We recently came across a set of stones sold to a client on a cruise ship and labelled as "Paraiba sapphire." They had purchased a set of relatively low-value topaz that had been artificially treated to mimic the color of a genuine paraiba tourmaline. When it comes to Paraiba tourmaline, the saying "if it's too good to be true, it usually is" has never been more pertinent. If you find low-cost Paraiba for sale, it is guaranteed not to be what you think it is. People looking to invest in genuine Paraiba tourmaline should only buy through trusted gemmologists or gem dealers and look for stones with legitimate certification.
Black:
Black tourmaline, often called schorl, is the most common variety of tourmaline. It is commonly seen in large, rough pieces. Metaphysically, it is a top-rated stone due to its strong protective properties. It obtains its brown to black colour from the inclusion of sodium and iron in its composition. It accounts for up to 95% of all the tourmaline material found. Due to its abundance, it usually commands very reasonable prices in comparison to other colour varieties.
Brown and yellow:
Brown and yellow tourmaline is often referred to as dravite and gets its colour from sodium magnesium inclusions. As unappealing as brown can sound, the colour range of brown tourmaline can be quite fetching with tones ranging from smoky brown, similar to smoky quartz, through to yellow/brown whiskey colours. While the varieties of dravite with sodium magnesium composition are brown and yellow, dravite with chromium or vanadium becomes chrome green, as seen above in the green tourmaline paragraph. See what I mean about the group names getting confusing?
Bi & Tri colour:
The terms bi-colour and tri-colour refer to a stone that contains two or three colours in one stone. This is a feature that does not occur in all stones. It requires a complicated sequence of events to occur during the formation of the stone, deep underground over many millions of years. I will attempt to outline an example of these events in a way that doesn't bore you with too much geology jargon.
When a stone begins to form in the earth, the perfect conditions for the growth of that particular stone are present. The proper heat, pressure, and minerals are there. In this case, the stone (a pink tourmaline) begins to do its thing and grow. Now, because nature is unpredictable at the best of times, something happens to interrupt that growth. The pink tourmaline stops growing. Now, the interrupting event has passed, but the conditions for growth have changed, so it is no longer possible for the pink tourmaline to continue to grow. Something is missing now; the mineral needed to form the pink colour. Instead, the conditions are perfect for a white layer to grow, so the white starts to form right where the pink left off. But wait! Another interruption. The white stopped growing just when it got going. Now the conditions have changed again. Now we have the correct minerals present to produce green tourmaline, so the green starts growing right over the top of the white. Millions of years go by, and one day somebody digs up this magnificent beauty……A tri-coloured watermelon tourmaline.
A true watermelon tourmaline gets its name from the green outer shell, fine white layer, and the pink middle representing the layers of an actual watermelon. As you can imagine, all of those conditions I just explained above create a reasonably volatile environment for growth, so it is not unusual to see watermelon tourmalines with quite a lot of inclusions. Inclusions in stones look like tiny cracks, fissures, and marks within the stone itself. Eye clean ( meaning no inclusions are visible to the naked eye), crystal clear stones are sometimes found and faceted for jewellery use, but the cleaner the stone, the higher the price. Without the white layer, it is not an actual watermelon but instead a bi-colour pink and green. Pink and green bi-colours are the more commonly seen bi-colour varieties. Still, from time to time, you might find a bi or tri-colour with different colour combinations like this blue and pink bi-colour specimen.
That will be a wrap on my tourmaline lesson for today. I really do love this mineral supergroup and could literally go on about them all day to anyone who will listen. Maybe you are already a tourmaline junkie like myself, or you are just discovering this stone for the first time. Either way, fair warning, it's a rabbit hole that once you go down, you will struggle to escape. The tourmaline collection is literally endless. Trust me, my gemstone-safe and depleted bank balance never lies.