Surprising element found in traces of Tycho Brahe’s alchemy lab confounds scientists

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While Danish astronomer Tycho Brahe is best known for his celestial discoveries made in the 16th century — before the invention of the telescope — he was also an alchemist who brewed secret medicines for elite clients. But what exactly Brahe worked on in his alchemical laboratory, located beneath his castle residence and observatory called Uraniborg, has been something of a historical enigma.

The covert nature of Brahe’s work was common among alchemists of the Renaissance, who kept their knowledge close to the vest. Today, only a few of his alchemical recipes remain. Uraniborg, situated on the island of Ven off the coast of Sweden and named for the muse of astronomy, Urania, was demolished after Brahe died in 1601.

Now, researchers who conducted a chemical analysis of glass and pottery shards recovered from the site where the Uraniborg once stood say they’ve uncovered new clues to what took place in the Renaissance scientist’s laboratory centuries ago.

The five shards studied in the new research were among those found during excavations carried out by another team from 1988 to 1992. Discovered in the remnants of a garden surrounding the site, the fragments were believed to have come from the alchemical laboratory.

Kaare Lund Rasmussen, a professor emeritus in the department of physics, chemistry and pharmacy at the University of Southern Denmark, was inspired to study the shards after wondering what insights they might offer into understanding Brahe’s alchemical work.

As lead author of the new research, he worked with coauthor Poul Grinder-Hansen, senior researcher and museum curator at the National Museum of Denmark in Copenhagen, on the investigation. Four of the shards contained higher concentrations of elements than expected, including nickel, copper, zinc, tin, mercury, gold and lead, the researchers reported Wednesday in the journal Heritage Science.

Gold was one substance Rasmussen already associated with Brahe. In an ongoing effort to understand why the Renaissance scientist died, Rasmussen coauthored a November 2016 study that analyzed some of Brahe’s hair and bones, and found excessive amounts of gold in his remains.

But the biggest revelation from the glass and pottery fragments in the new analysis — and the source of a separate mystery — was the presence of an element that wasn’t even known to scientists of Brahe’s time.

Rasmussen and his team were stunned to detect tungsten among the elements found on the inside and outside of the shards. During the Renaissance, mercury and gold were commonly used in recipes for medicines to treat a wide range of diseases, but the evidence of tungsten among them is “very mysterious,” he said.

“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?” Rasmussen said.

Swedish chemist Carl Wilhelm Scheele uncovered tungstic acid in the mineral now known as scheelite in 1781, more than 180 years following Brahe’s death. Not long after, Spanish chemists Juan José and Fausto d’Elhuyar y de Suvisa conducted follow-up experiments that successfully isolated tungsten, described in a paper published in 1783. The chemical element, also known as wolfram, occurs naturally in certain minerals.

It’s possible that tungsten appeared in Brahe’s lab through a mineral, or perhaps he processed one in a way that isolated the tungsten without Brahe realizing it, Rasmussen said.

There is also the chance that Brahe encountered tungsten through the work of German mineralogist Georgius…