A rare Bronze Age mould used to cast spearheads has been discovered under a barn in southeastern Moravia, Czech Republic. It just looked like a rectangular stone when the homeowner in the village of Morkvky first came across it while gardening in 2007, but when it was removed and examined by experts at the Archaeological Institute of the Moravian Museum, they discovered a very precisely modeled negative impression of spearhead on one side of the stone. That is a casting mould, also known as a matrix, used to make spearheads 3,000 years ago.Two of these molds would be used together to make a spearhead. The flat sides with the negative impressions would be matched up face-to-face and tied together with copper wire. A casting core was inserted into the opening to create a cavity for the hilt to be inserted into later. It was erected vertically and the bronze poured into the mould.It was not manufactured locally, or indeed anywhere within the borders of modern-day Czech Republic. It is tuff, volcanic rock indigenous to the Carpathian mountains. Comparisons with other stones indicate it came from the southeastern slopes of the Bkk Mountains, today eastern Hungary. The design of the spearhead, specifically the ribs on the blade and the sharp rib on the sheath, are typical of the Carpathian region.Researchers also analysed traces left in the stone using a spectrometer to determine the composition of the metal used in casting. The tests detected copper and tin, the two key components of bronze. []Although the stone itself may not look particularly impressive, it tells an important story. It shows that three thousand years ago weapons were already being produced in Moravia on a large scale, using technology that had travelled from far away.