Hey, could you maybe tell us about Labradorite? I checked wiki but I don't understand half the words there. I'm not a giant rock fan, but I like cool rocks and Labradorite looks really cool. Sorry to bother you!
Okay, so, Labradorite. Labradorite is complicated and sciencey, as all good rocks are. I’ll see if I can explain it in a way that makes any sense! (Once again, I’m not a scientist! Correct me if I’m wrong!)
Most minerals, when they’re bright and pretty and colorful, look like that because while they were forming some impurities got mixed into them - usually metals like iron, copper, or titanium. Without any impurities, these rocks would naturally be colorless. We call these guys allochromatic (other-colored).
Other gemstones are certain colors because those elements are an important part of how they formed. They’re not impurities that got mixed in, they’re actually part of the gemstone. Their natural color IS the color you’re seeing. We call them idiochromatic (inherently colored).
But labradorite doesn’t get its color from either of those things. Labradorite is special. It’s part of a third group: pseudochromatic (false colored). These rocks aren’t colorful at all, but they LOOK that way when light passes through them.
See, labradorite is actually just… grey. From most angles, it looks like this:
You have to look at labradorite from a pretty specific angle to get those flashy colors, so when we cut it into cabochons for jewelry, or just polish up big pieces of it, we’re careful to do so at the most flattering angle, the angle that shows the most schiller, or “those cool glowy colors.”
Why just the one angle? It’s all about labradorite’s crystal structure, and how it’s formed.
Labradorite is a rock that cooled down really slowly. Because of that, it’s made of lots of very very thin layers of crystal, stacked on top of each other and all pretty much aligned in the same direction. These are alternating layers of albite (mostly sodium), and orthoclase (mostly potassium), which solidify at very slightly different temperatures. Labradorite is a rock that cooled in just the right way for a thin layer of albite to form, then a thin layer of orthoclase, then another thin layer of albite, and so on.
When light hits labradorite at the perfect angle to pass through a bunch of these layers, you get the schiller effect. Basically, a little bit of the light gets bounced off the first layer and back to your eyes. The rest of the light passes through to the second layer, and a little bit gets bounced back to your eyes again, and so on. Every time more light gets sent back to you, it’s a little out of sync, and this makes it look like a different color.
(This is a very simplified way of explaining this.)
If these layers were all perfectly the same size, you’d get a uniform color, like the blue in moonstone. But in labradorite, these layers might be different widths in different places, so different parts of the stone will reflect back wildly different colors! We call this effect labradorescence to differentiate it from the uniform colored adularescence found in moonstone and some opals.
Depending on where it’s found in the world, labradorite can reflect all sorts of different colors!
But whatever color it is, Labradorite will always be the Best and Coolest Rock.
