Karak Resources Project

Mineralogical Characterization

Provenance studies of soils at archaeological sites often rely heavily upon chemical techniques such as ICP-AES. However, soils with very similar chemical composition can have different mineralogies (distinctive crystaline structures as well as variations within the same mineral) that are not revealed by multi-elemental techniques. Because mineralogical techniques are often cheap and usually nondestructive, beginning with mineralogy allows the researcher to gain valuable information and then to be selective about how many samples are submitted for expensive and somewhat destructive chemical analysis, thus conserving both valuable samples and funds.

Characterization techniques commonly employed in pedology, namely the use of scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX) analysis, X-ray diffraction (XRD), and photomicrograph were used to characterize the soils, slag, and plaster at the site. XRD analysis of bulk plaster samples showed that there are two main classes of plaster: calcite-rich (dominant) and gypsum-rich. Calcite-rich plaster consisted mainly of calcite and trace amounts of quartz. Photomicrograph and SEM-EDX analysis of the calcite-rich plaster revealed that calcite is a major mineral and Ca is a major element with Al and Si.

SEM and EDX analysis of gypsum-rich plaster showed that Ca and S are major elements.

XRD analysis showed that slag mineralogy consists mainly of K-feldspar (Leucite: KAlSi2O6), augite [Ca(Mg,Fe)Si2O6], calcite CaCO3), and maghemite (Fe2O3) with trace amounts of quartz. SEM and EDX analysis of slag showed that the chemical composition of slag is Si, Ca, K, Al, P, Ca, and Fe.