**Here’s what you’ll learn when you read this story:

• Researchers analyzed centuries-old shards from Tycho Brahe’s demolished observatory, revealing evidence of his secret basement alchemy lab and the metals he used to make elite medicines.
• The shards showed expected elements—but also tungsten, a surprise because it wasn’t officially identified until the 1780s, raising questions about whether Brahe used it intentionally or encountered it by accident.
• The finding highlights how Brahe blended astronomy and alchemy, using metals tied to planets and organs, while the true role of tungsten in his remedies remains unknown.

This story is a collaboration with Biography.com.

These days, we would call them proprietary blends. But in the late 1500s and early 1600s, individual alchemists called the medicines they cooked up in their labs ‘secrets’. And thanks to a study published in Heritage Science, we now know a little bit more about the secrets of one alchemist in particular.

It turns out that Tycho Brahe, mostly known for his study of astronomy, had his own basement laboratory for mixing medicines—including some particular elements.

Brahe’s famed observatory, located in his castle-like Uraniborg observatory on the island of Ven, in what is now Sweden, was dismantled following his death in 1601. But recently, a team of researchers from the University of Southern Denmark and National Museum of Denmark analyzed five shards rescued from what would have been the site’s old garden between 1988 and 1990. It’s believed those shards came from the basement alchemical laboratory.

The authors examined cross sections of the shards for 31 trace elements using mass spectrometry by converting sample molecules into charged ions. While there was plenty of the expected elements on the shards (four of which were glass and one of which was ceramic)—including nickel, copper, zin, tin, antimony, gold, mercury, and lead—there was one find that surprised the experts: tungsten.

“Tungsten is very mysterious,” Kaare Lund Rasmussen, archaeometry expert at the University of Southern Denmark, said in a statement. “Tungsten had not even been described at that time, so what should we infer from its presence on a shard from Tycho Brahe’s alchemy workshop?”

That’s a question that doesn’t have a clear answer. Rasmussen said that while tungsten does occur naturally in certain minerals, and could have made its way into Brahe’s laboratory that way, there’s another plausible theory: Brahe had a secret substance to help create his medicines for Europe’s elite.

Not classified as an element until the 1780s, tungsten likely first popped up in German chemistry as ‘Wolfram,’ and Brahe’s medicine were known to have German influence. “Maybe Tycho Brahe had heard about this and thus knew of tungsten’s existence,” Rasmussen speculated. “But this is not something we know or can say based on the analyses I have done. It is merely a possible theoretical explanation for why we find tungsten in the samples.”

“Most intriguing are the elements found in higher concentrations than expected,” Rasmussen said, “indicating enrichment and providing insight into the substances used in Tycho Brahe’s alchemical laboratory.”

The business of creating medicines was a secret one. Brahe, like others of the day, didn’t share the makeup of prescriptions. Brahe was known for his plague medicine—a highly complicated remedy to create that could have had up to 60 ingredients, including everything from snake flesh and opium to copper, oils, and herbs. Could the resulting medicine have also included tungsten as part of the finished product?

“It may seem strange that Tycho Brahe was involved in both astronomy and alchemy, but when one understands his worldview, it makes sense,” said Poul Grinder-Hansen, senior researcher and museum curator at the National Museum of Denmark, in a statement. “He believed that there were obvious connections between the heavenly bodies, early substances, and the body’s organs.”

Gold and mercury were often used by alchemists (including Brahe) in medicines, and it was common for alchemists to link the Earth’s elements to properties in space and the human body. And there’s a whole list of those connections. Silver tied to the Moon and the brain, while gold was a link to the Sun and the heart. Jupiter and the liver were connected through tin, Venus and copper by the kidneys, Saturn and the spleen by lead, Mars and the gallbladder by iron, and Mercury and the lungs by (of course) mercury. In this thinking, gold was a common ingredient for medicines of the day, including ones Brahe took.

Where tungsten fits into the mix, however, isn’t clear. So far, it remains a secret.

Tim Newcomb is a journalist based in the Pacific Northwest. He covers stadiums, sneakers, gear, infrastructure, and more for a variety of publications, including Popular Mechanics. His favorite interviews have included sit-downs with Roger Federer in Switzerland, Kobe Bryant in Los Angeles, and Tinker Hatfield in Portland.