For millennia, rich people and  royalty have surrounded themselves with the most valuable things  they could get their hands on.

Gold, silver, diamonds, and  emeralds have all been sought after by kings and queens for as  long as they’ve been around. But surprisingly, so was amethyst.

Sure, amethyst is pretty. But these days, you’re more likely to find it in the  rummage bin of a museum gift shop than in a wealthy person’s jewellery box. So what happened?

What’s behind the purple gem’s fall from grace? [Intro music] There’s a myth that the  Greek god of wine, Dionysus, was trying to woo a beautiful  maiden, whose name was Amethyste. But Amethyste didn’t want any of it, so she appealed to the goddess Artemis to keep her pure in the  face of Dionysus’s advances. Artemis protected her… by turning  her into pure, clear quartz.

Not sure if that’s what she had  in mind, but it was effective! Apparently, out of respect  for Amethyste’s sacrifice, Dionysus poured wine over the quartz, staining it purple and creating  the unique amethyst gem. Like Dionysus, humans have loved amethyst  since at least the time of the ancient Greeks.

The name comes from a Greek  word meaning ‘not drunk’, since they believed that the stone could  protect a person from intoxication. There’s no evidence to  suggest that’s actually true, but amethyst’s real backstory  does have some surprising facets. As the myth suggests, the mineral is a form of quartz  that has been colored purple.

But the stain comes from concentrations of iron scattered throughout the crystal structure. Depending on the amounts of each element, the color of amethyst can range  from a delicate pale lavender to a striking deep bluish purple. It’s typically found among igneous rocks, crystallizing inside empty  spaces to create geodes.

And these things can get big. The largest amethyst geode that’s ever been found is more than 5 and a half  meters tall and weighs 20 tons! But surprisingly, it wasn’t until recently  that scientists got a handle on how these beautiful gemstones formed.

Some thought they crystallised  from hot hydrothermal liquids, in the same way that many quartz veins do. Others suggested that they  formed from rainwater percolating through at lower temperatures. In 2024, scientists studying amethyst from Uruguay discovered that the fluids  that formed these crystals had the same chemical characteristics  as the nearby groundwater, and that it had crystallized at  temperatures as low as 15 degrees Celsius.

Just like water passing  through limestone can dissolve and redistribute calcium carbonate  to make elaborate cave formations, rainwater trickling through igneous rocks can sometimes dissolve and recrystallize  quartz and iron into amethyst. But that’s just part of the story. We’ve learned that there’s another  crucial factor in amethyst’s formation, and that’s radiation.

Igneous rocks are naturally radioactive, with unstable isotopes of  uranium, potassium and thorium decaying over millions of years and releasing their radiation  into the surrounding minerals. And it’s now thought that this radiation is what creates amethyst’s beautiful purple color. The natural radiation ionizes the  iron trapped inside the quartz, creating charged atoms that reflect purple light.

Radiation can continue to have  an effect on amethyst’s color after it’s been brought to the surface, too. The gem can fade if exposed to too much UV light, or it can have its intensity artificially  enhanced by treating it with X-ray radiation. Since amethyst is still fundamentally quartz, it has the same hardness and durability  as the common rock-forming mineral.

That makes it a great for use in jewelry and even practical objects like tableware. But really, it’s the color  that everyone cares about, and what makes amethyst the  most valuable form of quartz. In fact, for much of documented history, amethyst was one of the most  valuable gemstones of all.

Alongside diamond, ruby, sapphire and emerald, it was considered a so-called ‘cardinal’ gem, valued above all others  because of their intense color, religious significance and rarity. Among these, amethyst was of  particular interest to royalty because it was purple – a color that  was very difficult to find in nature or synthesize artificially. So it became a symbol of the richest and most powerful people who could obtain it.

This obsession with purple goes  way back to the ancient Egyptians. Archeological evidence shows  that amethyst was mined at a place called Wadi el Hudi  in Egypt’s eastern desert. Inscriptions from the Middle Kingdom, between 2000 and 1700 BCE, describe workforces of up to 1500  men setting out on expeditions to find and extract the precious gem.

But because the mineral’s  color fades in the sunlight … something that’s in abundance in the desert … the rocks wouldn’t have  been visible on the surface. It would have taken a lot of  labor-intensive trial and error to find veins and pockets of them. Despite this, amethyst stones feature heavily in royal burials from this period.

And the Egyptians’ love for  the purple crystal continued right up until the end of the age of the Pharaohs. Cleopatra supposedly wore an amethyst  ring during her relationships with Mark Antony and Caesar, which may have inspired the Roman elite  to adopt this purple gem of power too. At the same time, the Greeks really leaned into the idea that the stone could ward off drunkenness.

They carved wine goblets out amethyst, and held the crystals in their mouths while drinking in the hopes  of staying sober and serious. But it was more than just a hangover-avoider. Amethyst was found in a Bronze age  Mycenean warrior’s tomb as well, suggesting it was also considered  valuable for its own sake.

Continuing into the Middle Ages, in Europe, priests and bishops often wore amethyst  as a symbol of faith and piety, although that association with power probably wasn’t lost on  their congregations either. And during the reign of Catherine  the Great in 18th Century Russia, high-quality dark-colored amethyst was discovered in the Ural Mountains. Catherine reportedly collected as much  of the purple gemstone as possible, and had thousands of pieces set into jewelry.

Clearly, our love for the purple  gem stood the test of time. But starting around 200 years ago, amethyst suddenly became a gem that everyone could aspire to owning. One of the things that had made  amethyst so valuable was its rarity.

That changed around 1820, when immigrants from Germany  colonized the southern tip of Brazil. As they built their settlements in the area now known as Rio Grande do Sul, they discovered huge deposits of  amethyst in the basaltic bedrock. Around 130 million years ago, lava flooded over what is now southern Brazil.

This basaltic lava solidified  into dense black rock rich in iron and with lots of gas pockets trapped within it, which proved to be the perfect  place for amethyst to grow. The colonists mined the amethyst with hand tools and, later, heavy machinery. They shipped the crystals back to Germany, where they were cleaned up and sold.

In time, Rio Grande Do Sul became the  biggest producer of amethyst in the world. he region now exports some 400  tonnes of the crystal per month. This isn’t the only place in Brazil that has  been pouring amethyst into the market, either. In the northern part of the country, another amethyst deposit dates  back nearly 2 billion years, but was only discovered in the 1980s.

And some of the finest  amethyst crystals in the world have been found in Brazilian river  deposits, weathered out of the mountains. The story goes that these gems were discovered during a boar hunt in 1979. After the boar disappeared  into a crack in the rock, hunters started digging in pursuit, but soon found a much better prize in  the shape of a large amethyst crystal.

Thanks to this huge influx  of amethyst from Brazil, as well as other finds in  Canada, Zambia and Uruguay, the purple mineral has now been  downgraded from a precious, cardinal gem to a semi-precious stone. It’s still as beautiful as it ever was, but not so rare that it’s prohibitively expensive. Which is handy for us, because it happens to be this  month’s Rocks Box mineral!

Every month, we send our SciShow Rocks  Box subscribers a stone or fossil with a story to tell. If you’d like to join, visit SciShow. Rocks or click the link in the description.

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