## 3 Results and Discussion
### PXRD Analysis  
Ancient iron slags are mainly constituted of iron-bearing silicate minerals: olivine, typically fayalite (Fe\({}_{2}\)SiO\({}_{4}\)), pyroxene, frequently hedenbergite (CaFe\({}^{2+}\)Si\({}_{2}\)O\({}_{6}\)), and glass, with iron oxide-hydroxide minerals--mostly wustite (FeO), magnetite (Fe\({}_{3}\)O\({}_{4}\)), goethite (\(\alpha\)-FeO(OH)), and metallic iron as minor common components. Short range mineralogical variations seen in slags suggest that, during formation, there were relative unstable oxygen and temperature conditions [21]. According to their mineral composition, iron slags can be divided into two main classes [22]. The first type is principally constituted of the typical iron oxide-hydroxide minerals: wustite, magnetite, and the weathering products goethite and lepidocrocite (\(\gamma\)-FeO(OH)); then, an appreciable amount of quartz (SiO\({}_{2}\)), glassy phases, and metallic iron. Wustite is very common in bloomery slag; in smithing slag; where, during the slag formation, the temperature and/or oxygen content are high, instead of wustite, magnetite occurs instead. Glass forms from the'residual melt' and may vary considerably, depending on which minerals had previously crystallized, the total composition of the slag, and the progress of cooling. Droplets of few micrometers sized metallic iron formed during the reduction process are also common slag inclusions. The major mineral phases of the more common second type are pyroxenes (hedenbergite), olivines (fayalite), and iron oxides, although olivine minerals and wustite could be present only in small quantities or absent. The presence of (usually smaller quantities) of other minerals formed by firing at over 900 \({}^{\circ}\)C--mullite (Al\({}_{6}\)Si\({}_{2}\)O\({}_{13}\)), cristobalite (SiO\({}_{2}\)), pyrolusite (MnO\({}_{2}\)), akermanite (Ca\({}_{2}\)Mg(Si\({}_{2}\)O\({}_{7}\))), etc.--can be ascribed on the account of furnace or smith's hearth linings; the silica polymorph cristobalite formed actually suggests a heating temperature of at least 1200 \({}^{\circ}\)C.  
In case of the iron slag samples being selected for PXRD investigation, only part of the mineral components visible by petrographic microscopy [8] could be confirmed. While on the diffractograms recorded (Figure 2) some of the anterior detected minerals (quartz, cristobalite, goethite, magnetite, pyroxene) can be reliably identified, confirmation of the presence (and evaluation of the quantity) of other phases is difficult. Most of the finely disseminated, microscopically visible silicates crystallized in the glassy matrix (the fayalite and the coexisting hedenbergite) and part of the iron oxides (magnetite, haematite, wustite) could not be reliably evidenced due to the complex superposition of the minerals' individual PXRD pattern and to the signal degradation caused by the firing caused vitrification in addition to the amorphization occurring due to the burial environmental circumstances [23; 24; 25]. The semiquantitatively estimated most important components of the PXRD-analyzed samples are presented in Table 6.  
Except for the Vat (Vatava) sample (very poor in quartz), the dominant crystalline phase is quartz, followed by cristobalite (though in some samples only in traces) and the (most probably weathering product) goethite. A large quantity of amorphous and/or glassy material was also evidenced. Magnetite and hedenbergite were detected in traces in most samples or were absent. Fayalite and wustite, practically mandatory in iron slags, are not evidenced, except for the Vat sample deriving from the Vatava site (Figure 2). The analcine (NaAlSi\({}_{2}\)O\({}_{6}\):H\({}_{2}\)O) in the 4264 sample (Calugareni), as well as the clinoclase (Cu\({}_{3}\)AsO\({}_{4}\)(OH)\({}_{3}\)) and dolomite (CaMg(CO\({}_{3}\))\({}_{2}\)) in the Vat (Vatava) sample, could appear accidentally as they aren't really confirmed by the elemental analysis results.