Crucible fragments were collected from the excavation of the prehistoric copper mining site of Phu Lon located near Ban Noi, Amphoe Sang Khom, Changwat Nong Khai, Northeastern Thailand. The specimens came from the matrix of a single cultural horizon of a major excavation locus known as Pottery Flat. The matrix was composed principally of crushed host rock from the mine in association with domestic pottery, stone adzes, and stone bracelets dating to the first millennium. The ore deposit at Phu Lon is a typical contact metasomatic deposit consisting of a sulphide ore body with an indigenous oxide zone exposed at the surface. The mining area is an extensively weathered skarn deposit cut by numerous late stage quartz veins. Charcoal is abundant here and it appears that the dressed ore was smelted in crucibles, a process that would leave little slag. The absence of any quantity of smelting slag in the debris could also indicate that melting and casting were important processes as well. Analytical work on the crucible fragments includes preliminary studies with the binocular microscope, thin section and oil immersion work with petrographic microscope, scanning electron microscopy (SEM) with accompanying energy dispersive spectrometry (EDS), X-ray diffraction studies (XRD), and PIXE analyses (proton induced X-ray emission) of prills. Polished sections of prills for metallographic and SEM-EDS studies have also been prepared. The results of initial studies are presented here but more detailed results of the completed project will be presented at a later date.