Feldspars are very common minerals in the Earth’s crust. Their name derives from the German for ‘field crystal’ and refers to the fact they are minerals that do not contain ore. With one or two exceptions, they are of low economic value.
The provincial mineral of Newfoundland and Labrador is a feldspar, however, and it doesn’t need to yield ore. Thanks to its unique structure, it contains something rather more wonderful. It has magic locked within.
That magical mineral is labradorite, a variety of feldspar rich in calcium. It is normally grey, white or almost transparent. In the right light, however, it suddenly reveals a secret inner self and shows off a glowing heart of ice and fire. Quite why has been a subject of myth and mystery for centuries.
Fire and ice
It was named ‘Labradorstein’ in the 18th century after Moravian missionaries in Nain brought it to the attention of European naturalists. The type locality is Paul’s Island, where the geology is dominated by a huge mass of crystalline rock – anorthosite – composed of almost nothing but labradorite.
In igneous rocks that cooled from iron- and magnesium-rich magma, labradorite is one of the most common components. If the magma cools slowly, the labradorite is one of the first compounds to begin solidifying from the melt. It thus has time to grow into large crystals that interlock and bond together. Being buoyant in comparison with the molten remainder, the labradorite-rich mush then begins hardening in the Earth’s crust, whilst the denser fluid sinks down to greater depths.
In the case of Nain, this process took place about 1.3 billion years ago. The molten rock insinuated itself into a huge fracture system deep beneath the Earth. This wrenched-apart crust is known as the Abloviak shear zone, and is half-a-billion years older still.
Such magnitudes of time may be impossible to comprehend, but the processes can at least be examined and interpreted from the rock types and structures. It is thought that the 1.8 billion year-old shear zone was formed during a period of mountain-building called the Torngat orogen. Plate tectonics dragged two previously separate landmasses – the Nain province and the Churchill province – together, producing a continental suture zone.
Smashed and welded together, Nain and Churchill formed a high mountain range, but eventually the stresses became too much, and they began trying to separate. As Bob Dylan almost sang, it was destiny which pulled them down and gravity which broke them apart.
As the fractures at the root of their union began to open up, however, so their progeny – the molten rock created by the heat of their embrace – worked to hold them together. Like a furious, tenacious toddler clinging to its parents, the magma squeezed itself up, froze in place, and stopped them breaking away. The two continents would now be married forever; united by labradorite.
Millions of years later, erosion and tectonics brought the rocks up to the surface, where (eventually) humans came eye-to-eye with the mineral’s extraordinary optical properties. It is said that the first Labradorians to see it thought it was the northern lights made stone: the aurora borealis trapped inside a crystal. As a description it is hard to improve upon.
Powers, real and imagined
The brilliant play of colours is a phenomenon known as a schiller effect. It occurs in a few feldspars, and its resemblance to a lunar glow shimmering on water means they are sometimes referred to as moonstones. This turns out to be remarkably literal: feldspar-rich anorthosite is the oldest rock in the crust of our satellite.
The light of labradorite is so unusual though, that it has been given its own name: labradorescence. Scientifically, it is now known to derive from the scattering of light by internal layers that formed as the labradorite crystals grew. As the lamellae aren’t perfectly parallel (the name anorthosite means ‘not straight’), the light misbehaves when it hits them, producing the extraordinary interference colours.
Unsurprisingly, these idiosyncrasies give labradorite a commercial character. The anorthosite of Nain is a globally popular decorative building stone, the labradorite itself a semi-precious stone, a mineral that can be made to shine by a skilful craftsperson.
Sadly, it is also a money-maker for various charlatans who make ridiculous claims of its properties.
‘[W]earing labradorite allows one’s innate magical powers to surface,’ barks one online loon. It doesn’t. Labradorite ‘alleviates rheumatism and gout’ claims another, without a shred of evidence.
A third offering – that the mineral is ‘beneficial to the lungs’ – is actually dangerous. Labradorite is a key component of many highly explosive volcanic ashes, such as in the Soufriere Hills of Montserrat, and inhaling the particles can cause acute and chronic respiratory diseases.
There is nothing in the slightest wrong with taking pleasure from such a marvelous mineral. It is wholly understandable. To imbue an inert substance with special powers and use them as a marketing tool is quite another thing, and quite wrong.
Labradorite is ancient, tough and, when properly illuminated, simply beautiful. The essence of Labrador, perhaps. That really should be sufficient.