A mold for casting an oxhide ingot was discovered in the LBA north palace at Ras Ibn Hani in Syria. It is made of fine-grained "ramleh", a shelly limestone. Archaeologists found burnt copper droplets around the mold. In spite of the questionable durability of limestone, Paul Craddock et al. concluded that limestone can be used for casting “large simple shapes” such as oxhide ingots. Evolution of carbon dioxide from the limestone would damage the metal surface that touched the mold. Thus, metal objects requiring surface detail could not be produced successfully.
This is not to say that oxhide ingots were normally cast in limestone molds. Using an experimental clay mold, Bass et al. argue that the ingot's smooth side was in contact with the mold while its rough side was exposed to the atmosphere. The roughness results from the interaction of the atmosphere and the cooling metal.