Man in Czech Republic accidentally finds Bronze Age spearhead mold in his backyard

A seemingly dull rectangular stone, used as part of a foundation for an old barn in a Czech garden, is actually half of a rare Bronze Age mold used to make spearheads, a new study finds.

The almost 9-inch-long (23 centimeters) mold, carved into a volcanic rock known as rhyolite tuff, dates to the Late Bronze Age, around 1350 B.C.

"This is the best preserved and most perfect casting mold for a bronze spearhead in Central Europe," study first author Milan Salaš, an archaeologist at the Moravian Museum in the Czech Republic, told Live Science in an email. "Based on the shape of the spearhead and the type of raw material used … the mold was imported to southern Moravia from northern Hungary."

The newfound 2.4-pound (1.1 kilograms) mold matches others from the Urnfield culture, which emerged during the mid-second millennium B.C. and is known for cremating and burying the dead in urns in field cemeteries.

In their analysis, Salas and his colleagues wrote how molds like this one made it possible to cast metal tools and weapons, such as spearheads, axes and daggers, with greater uniformity. This, in turn, would have made armed conflict easier to sustain, and also strengthened the trade and political power of cultures in the Carpathian Basin of Central Europe, they wrote in the study, which was published in the journal Archeologické Rozhledy (Czech for "Archaeological Views") in 2025.

"These types of spearheads, characterized by ribs along the blade and a sharp ridge on the socket, are common in the Carpathian region," Salaš told Radio Prague International, the official international broadcasting station of the Czech Republic. "It was essentially [a] serial production. As we can see, the mould was used very intensively. Possibly dozens of spearheads were cast from it."

The stone was discovered by homeowner J. Tomanec in 2007, after he noticed the gray slab sticking slightly out of the ground, where it likely fell after being used in a barn foundation. In 2019, Tomanec gave the stone to the Moravian Museum, where Salaš examined it more closely using X-ray fluorescence scans to determine which elements made up the mold.

"It was proven that bronze was cast in the mold and that both halves of the mold were held together with copper wire," Salaš told Live Science via email.

The mold's backstory

To trace the mold's origins, study co-author Antonín Přichystal, a professor of geology at Masaryk University, worked with Salaš and used X-ray diffraction, a technique that determines the atomic structure of certain crystalline solids, like stone. This determined that the mold was made out of rhyolite tuff, which is commonly found in the Bükk Mountains in Hungary or around the nearby city of Salgótarján.

About 20 million years ago, there was a huge volcano in the area that produced an "enormous quantity of the tuff," Přichystal said. "Unfortunately, we are not able to determine precisely the site where the mold was prepared but generally its provenance is evident (northern Hungary up to southeastern Slovakia)," he told Live Science in an email.

While other Bronze Age weapons and armor have been found in nearby areas in the Carpathian Basin, the mold gives a behind-the-scenes look at how these items were created.

"In this case, heavy scorching and traces of heat clearly demonstrate its repeated use and the serial production of bronze castings," Salaš said.

Oftentimes, Urnfield-period casting molds are found at settlements; more rarely, they're uncovered in burials as grave goods. It's unclear how a spearhead mold from the Urnfield culture ended up in the man's yard, but it was "most likely redeposited in modern times from an Urnfield Period site in the vicinity," the authors wrote in the study."

This interesting case shows how long the journey from the discovery of a unique archaeological object (2007) to its scientific evaluation in a professional journal (2025) can sometimes be," Přichystal said.

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