## 3 Results and Discussion  
### Elemental Analysis  
Archaeological iron slag is a complex, heterogeneous material with the major constitutive elements Al, Si, K, Ca, Ti, Mn, Fe, Sr, Zr, and Ba. The presence and the concentration level of Al, Si, Ca, Mn, Sr, and Ba are related to the choice of fluxes; K and Ca level is able to indicate the fuel sources used, while Fe, Ti, and Zr levels are indicative of the iron ore source [6]. Surface elemental composition data of the slags are presented in Table 2 (major elements) and Table 3 (trace elements); the measurements were carried out in three different superficial points of the carefully cleaned finds. The mean surface elemental concentration values offer a good view on the samples' mineral-chemical heterogeneity. The major elemental composition (Table 2) is dominated by Fe. Ca level is rather low, otherwise the slags are also poor in other major lithophile elements (notice that Na, Si, and Al could not be determined). Ti (2500-5500 ppm) was detected in samples 4264, 4009, 4169, 4222 (Calugareni-_vicus_, Cal-v), 9487,9454 (Brancovenesti-_retentura_, Br-r) and Vat (Vatava, _East of the_ tower), while Ba (500-1500 ppm) in 4251, 4264, 4169, 4222 (Cal-v), 9487, 9445, and 9454 (Br-_r_). Mn (500-5500 ppm) and Sr (120-250 ppm) are overall present. The slag surfaces are very poor in volatiles; however, in some samples, detectable amounts of As (4169) and Br (4137, 4251, 9445, 9454, Vat) were found. The surfaces are relatively poor in trace elements too (Table 3). Co (at relatively high level) and Rb are present in all samples; in some cases, Zn (4251, 4264, 4169, 4222, 9487, 9454), Mo, and Pb (4137, 4251, 4009, 4169, 4222, 9487, 9445, 9454, Vat), respectively Bi (4137, 4251, 4009, 4169, 9445, 9454, Vat) were detected in significant amounts. Cu appears in measurable amount in two samples only (4169, 4222). The somewhat surprising presence of gold on the surface of samples 4137, 9454, and Vat was confirmed microscopically [8] (Au globules embedded by \"accidental\" contamination?). It should be noted that Au doesn't appear in the PXRF or the ICP-MS bulk results. \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline  & & & & & & & & & & & \\ \cline{3-11} \multirow{3}{*}{**Element**} & \multirow{3}{*}{**4137**} & **4251** & **4264** & **  
PXRF bulk data (Table 4) generally agree with the similarly determined surface data; however, there are some differences. The dominant lithophile element of the bulk is Fe. Ca level is relatively low, the slags being generally poor in lithophiles excepting Fe. On the surface, K is not detected, and even in the bulk appears in sample 4264 only (9500 mg kg\({}^{-1}\)). Contrary to the surface data where Ti is present in almost all samples, in the bulk samples, PXRF is detected in 4264 and 4009 alone (3500-4500 mg kg\({}^{-1}\)). Ba is present in all Brancovenesti and Calugareni samples, missing that from Vatava (Vat). Concerning the trace elements, Cu is present in sample 4264 only; Zn in 4137, 4251, 4264, 4009; and As in 9454. Rb is missing from 9445, Mo from 4264, Pb from 4264, and Bi from 4264 and 4009. Sn appears in samples 4251, 9487, and 9445. Br, originating probably from the local wood fuel used [14; 15], is overall present. ICP-MS data of the samples' bulk elemental composition are presented in Table 5 (according to the value given by the measuring instrument, LOD is overall 0.02 mg kg\({}^{-1}\)). PXRF and ICP-MS bulk data differ significantly, as both the required sample preparation methodology and the concentration ranges characterizing the analytical methods are different (for example, measuring the same samples by using the more sensitive ICP-MS method, the presence and concentration level of further trace elements--Cr, Ni, Ag, Cd, Sb, I--could be determined, whilst Ca and Br couldn't be measured). Commonly, it can be stated that, at concentration levels of 50-100 mg kg\({}^{-1}\) or more, PXRF data should be considered more reliable, while, below 50 mg kg\({}^{-1}\), the ICP-MS values are more creditable [16; 17].