Introduction

The working of metal has played such a crucial role in the evolution of human civilization that historians conventionally divide ancient eras into “metal” ages, taking into account the use of copper, bronze, and iron in sequence. However, it is clear that sharp breaks in these periods are conventional. In particular, the start of the iron age has long been discussed.

Ancient Egypt had great mineral resources. The wide desert areas, in particular the Eastern desert, are rich in mines and quarries, which have been exploited since ancient times (Ogden 2000; Klemm and Klemm 2008; Lucas and Harris 2012). Copper, bronze, and gold have been used since the 4th millennium BCE (Ogden 2000). In contrast, despite the significant presence of iron ores in ancient Egypt (Ogden 2000; Lucas and Harris 2012), the utilitarian use of iron in the Nile Valley occurred later than in neighboring countries, with the earliest references to iron smelting dating to the 1st millennium BCE (Tylecote 1992; Waldbaum 1999; Ogden 2000).

The sporadic use of iron during the Bronze Age has been reported in Egypt and the Mediterranean (Photos 1989; Tylecote 1992; Waldbaum 1999; Ogden 2000). A handful of iron objects likely dates to the Old Kingdom (3rd millennium BCE) onward (Waldbaum 1999; Ogden 2000), with the most ancient iron ones dated to about 3200 BCE (Stevenson 2009). It is generally assumed that early iron objects were produced from meteoritic material, despite the rare existence of smelted iron fortuitously obtained as a by‐product of copper and bronze smelting (Bjorkman 1973; Photos 1989; Tylecote 1992; Bard 1999; Waldbaum 1999; Ogden 2000). During the Bronze Age, iron was definitely rare, its value was greater than that of gold (Burney 2004), and it was primarily used for the production of ornamental, ritual, and ceremonial objects (Bjorkman 1973; Tylecote 1992; Waldbaum 1999). This suggests that either early iron artifacts were unsuitable for utilitarian and military purposes or working techniques for producing the metal in large quantities had not yet been mastered (Waldbaum 1999). By the end of the 2nd millennium BCE, iron had come into common use in most of the eastern Mediterranean, although the rates at which it was substituted for bronze vary from region to region (Tylecote 1992; Waldbaum 1999; Ogden 2000).

Over the past 50 years, the interest in the use of meteoritic iron and in the introduction and spread of iron smelting technology in the Mediterranean area has increased steadily (Bjorkman 1973; Photos 1989; Tylecote 1992). Different historical and philological studies have addressed these topics (Piaskowski 1982; Photos 1989). Compositional and structural analyses of ancient iron findings have been performed and reported (Bjorkman 1973; Photos 1989; Waldbaum 1999), but despite few cases (Johnson et al. 2013; Rehren et al. 2013), the common lack of detailed information on analytical methods and of robust data hinders their utility in answering broader questions (Photos 1989; Waldbaum 1999). Investigations are further hampered by the difficulty in obtaining permissions to analyze rare and precious artifacts with either destructive or nondestructive techniques (Photos 1989).

Beyond the Mediterranean area, the fall of meteorites was perceived as a divine message in other ancient cultures. It is generally accepted that other civilizations around the world, including the Inuit people; the ancient civilizations in Tibet, Syria and Mesopotamia (Buchwald 2005; Buchner et al. 2012); and the prehistoric Hopewell people living in Eastern North America from 400 BCE to 400 CE, used meteoritic iron for the production of small tools and ceremonial objects (Prufer 1962). Nonetheless, only few detailed scientific analyses have clearly reported the identification of meteoritic iron in ancient artifacts. These include several iron tools made by the Inuit people in Greenland, recognized as being made of small fragments of the Cape York iron meteorite shower (Buchwald 1992); the ancient “iron man” Buddhist sculpture, likely carved from a fragment of the Chinga meteorite (Buchner et al. 2012); two funerary iron bracelets and an axe excavated in two different Polish archaeological sites (Kotowiecki 2004); and, less recently, a few masses of meteoritic iron from the Hopewell culture (Prufer 1962).

Of the rare surviving examples of iron objects from ancient Egyptian culture, the most famous is the dagger from the tomb of the ancient Egyptian King Tutankhamun. The history of King Tutankhamun (18th dynasty, 14th C. BCE) has fascinated scientists and the general public since the discovery of his spectacular tomb in 1922 by archaeologist Howard Carter (Carter and Mace 1923‐1927‐1933). In 1925, Carter found two daggers in the wrapping of the mummy: one on the right thigh with a blade of iron (Fig. 1) and the other on the abdomen with a blade of gold (Carter and Mace 1923‐1927‐1933). The former (Carter no. 256K, JE 61585) is the object of our study. The dagger has a finely manufactured blade, made of nonrusted, apparently homogeneous metal (Fig. 2). Its handle is made of fine gold, is decorated with cloisonné and granulation work, and ends with a pommel of rock crystal (Feldman 2006; Zaki 2008). Its gold sheath is decorated with a floral lily motif on one side and with a feathers pattern on the other side, terminating with a jackal's head.1

Figure 1 Open in figure viewer PowerPoint The mummy of King Tutankhamun. Black and white picture of Tutankhamun mummy showing the iron dagger (34.2 cm long) placed on the right thigh (arrowed). Copyright Griffith Institute, University of Oxford.

Figure 2 Open in figure viewer PowerPoint The iron dagger of King Tutankhamun. Color picture of the iron dagger (Carter no. 256K, JE 61585) with its gold sheath. The full length of the dagger is 34.2 cm.

Among the iron objects discovered in Tutankhamun's tomb, which also include 16 miniature iron blades, a miniature head rest, and a bracelet with the Udjat eye of iron,2 the dagger is the one that has most attracted interest from archaeologists and historians, mainly in relation to the origin of the metal and to the employed working technology (Bjorkman 1973; Photos 1989; Tylecote 1992; Waldbaum 1999; Johnson et al. 2013). As already observed by Carter, the iron objects from Tutankhamun's tomb highlight some innovative features of the use and trade of iron in the Late Bronze Age (Carter and Mace 1923‐1927‐1933). Interestingly, diplomatic documents from the Egyptian royal archives from the 14th C. BCE (the Amarna letters) mention royal gifts made of iron in the period immediately before the Tutankhamun's reign. In particular, it is reported that Tushratta, King of Mitanni, sent precious iron objects to Amenhotep III, who may have been the grandfather of Tutankhamun. Daggers with iron blades and a gilded iron hand bracelet are mentioned in the list (McNutt 1990; Morkot 2010; Lucas and Harris 2012; Rainey 2014).

Results of previous analyses of Tutankhamun's iron funerary objects have proved controversial. Bjorkman (1973) referred to a meteoritic origin of the iron dagger on the basis of its high nickel content determined through an analytical study performed in 1970; however, to the best of our knowledge, this study has not been published and the analytical techniques used at that time were not specified. In 1994, analysis of the dagger's iron blade by X‐ray fluorescence (XRF) spectrometry revealed a Ni content of 2.8 wt%, which was considered inconsistent with meteoritic iron by the authors (Helmi and Barakat 1995).

Iron meteorites are mostly made of Fe and Ni, with minor quantities of Co, P, S, and C, and trace amounts of other siderophile and chalcophile elements (Haak and McCoy 2003). Their chemical compositions are typically determined by means of sensitive, yet destructive, analytical methods, including instrumental neutron activation analysis (Wasson and Sedwick 1969) and inductively coupled plasma mass spectrometry (D'Orazio and Folco 2003). XRF measurements, carried out in the laboratory and, more recently, with the aid of portable or handheld devices, have been widely used for the bulk nondestructive analysis of meteorites since the late 1960s and early 1970s (Reed 1972; Zurfluh et al. 2011; Gemelli et al. 2015).

In this work, we have determined the bulk composition of the Tutankhamun's iron dagger blade using state‐of‐the‐art, nondestructive XRF analysis. In the last 20 years, a dramatic improvement in solid‐state detectors technology has allowed new analytical applications. Modern energy dispersive XRF spectrometers exhibit typical energy resolutions below 140 eV @ Mn Kα line (West et al. 2013), allowing the deconvolution of close peaks (Redus and Huber 2012), as required for correctly estimating minor amounts of cobalt in meteoritic irons.