Block of the Week: Emerald

Cashing in the green

Ah, to be minted with the green stuff. To swan about the villages of the Overworld with pockets bursting with emeralds. “Ho there, villager!” you would bellow, tossing a few emeralds for a handful of carrots. You’d never need farm again!

Also, you could build a house of blocks of emeralds! That’d be one in the eye for your neighbours, those ones with that showy mansion of quartz. Build your house out of money! Ha! That’ll show ‘em!

Oh, one can dream. Emeralds are pretty rare in Minecraft, their ore only found in Extreme Hills biomes, and even there it’s super scarce. In the real world emeralds are found in many countries, from Cambodia to Canada, but only rarely, and it’s rarer still to find one without cracks and fissures through it.

Hi there, little emerald, peeping out of your calcite bed! Check out its hexagonal cross-section, a feature of emerald’s atomic structure. Pic by Rob Lavinsky.

While emeralds are good money in Minecraft, their prices in reality vary wildly because there’s no fixed market. Take the Bahia Emerald, which was mined in Brazil and is one of the largest emeralds yet found, its stone weighing 340kg. But no one can quite work out how much it’s worth. One valuation pegged it at $370 million. It was once put on eBay with a Buy It Now price of $75 million. One offer was made for $19 million. But right now it’s sitting in a Los Angles County Sheriff’s vault, having been recovered after being stolen, and no one can quite work out who owns it.

Still, emerald is pretty special stuff. It’s made out of beryllium, a pretty rare element which is formed when cosmic rays collide. Yes, it’s made in SPACE when particles travelling near the SPEED OF LIGHT crash into each other. And then it becomes part of stars and planets, and...

OH, THE INFINITE MAJESTY OF THE UNIVERSE.

When this trapiche emerald was formed, nearby carbon was pulled within, creating a black, six-pointed star. There's no scientific consensus on exactly how this happens - but it's rather beguiling, no? Picture by Luciana Barbosa.

Oh, where were we? Ah yeah, emeralds. So we’ve got a small deposit of beryllium in the Earth’s crust, and now we’re going to heat it to 400 degrees centigrade and apply to it pressure of between 1000 and 3000 kg per square centimetre.

Now, this makes the mineral called beryl. To get emerald, you need a little chromium or vanadium nearby during the process, because it’s these elements that give emerald its green colour. Pure beryl is colourless, after all. In fact, in 13th century Italy, it was used to make the lens of eyeglasses.

You can also get slightly blueish or yellowish emerald if you add the slightest dash of iron, but go too far and you’ll get fully yellow helidor, or light blue aquamarine. Gem experts can get awfully shirty about the distinctions between these different colours, despite them fundamentally being the same stuff.

The Gachalá Emerald is a 172 gram chunk of green heaven, found in 1967. Now housed by the Smithsonian Institution, it's one of the world's most valuable emeralds. Thanks to thisisbossi for the photo! Hope you didn’t try to steal it!

Hopefully you’re now getting an appreciation for why emeralds are so rare. Beryllium doesn’t often form clumps large enough to form beryl, and then you need just the right amounts of chromium or vanadium around to avoid gem-nerds getting all hoity-toity about the perfection of your gem’s colour.

And even then you don’t know how much it’s worth. Money, schmoney! The important thing is remembering your emerald’s origins: COSMIC RAYS COLLIDING IN SPACE. That’s got be worth something.