This book, in one sense, has been long awaited, since the materials described in it were indeed excavated in 1912, and some were the subject of a seminal but now largely forgotten paper by C. H. Mathewson published in 1915. I always remember this paper because on a contiguous page of the journal was the announcement of the death of Henry Gwyn Jeffreys Moseley (23 November 1887–10 August 1915), the scientist who made XRF analysis possible. The paper was, in another sense, rediscovered after the Second World War, since practically no attention had been paid to it in the interim. Now, some 90 years later, this excellent monograph on the metallic antiquities of Machu Picchu has appeared, completing the story of this investigation.

Some of the research work, carried out by R. B. Gordon, was clearly performed some time ago, since the author notes that the metallographic examinations were recorded on a 3.5 × 4.5-inch Polaroid film; some were rephotographed between 2005 and 2007 employing a digital camera. In 1915, Mathewson had determined the elemental composition of 31 of the bronze objects, work augmented with EDAX data from 1981 to 1985, with additional EPMA data acquired between 2004 and 2005, including data for silver-copper alloys that had not been investigated by Mathewson. An interesting aspect of the work is the fine attention to detail. For example, between 2004 and 2005, several laboratory silver-copper alloys were fabricated that duplicated the compositional data for some of the silver alloys from Machu Picchu. Unusually for a South American context, the alloys used to make the tumis, tupus, awls, axes, chisels, lime spoons, and so forth from Machu Picchu were all made of either silver-copper alloys, tin bronzes, or metallic tin. There appears to be no arsenical copper or arsenical bronze, nor gold or tumbaga alloys in the collection of excavated material. The decidedly prosaic nature of the metallic materials may be a consequence, as Burger and Salazar suggest, of the deceased members of the Inca ruling and religious elite taking their more prestigious materials with them in burial elsewhere. The abundance of silver-copper alloy pins shows that this alloy was sufficiently common that most families of artisans and retainers could own their own. The majority of these pins were found with cloth embedded in the encrusting corrosion, showing that they were worn with clothing at burial. It is a pity that no scientific work was carried out on the corrosion products themselves, by Debye-Scherrer power X-ray diffraction, for example, especially since a number of interesting compounds are associated with human burial adjacencies. Work by Sibley and Jakes has also shown that traces of organic molecules survive in mineralized textiles, and of course, the weave and weft of the fibers is often well preserved; it should be reported in any comprehensive account of the metallic antiquities from the site, especially if SEM examination is available, as it was in this case.

It is interesting that a disk had been plated with silver. It was examined using SEM by Rutledge, who found a layer of pure silver over the bronze; the authors speculate that the electrochemical replacement technology had been employed in this case for the deposition of the silver. However, no SEM photomicrographic evidence is presented to substantiate this conclusion, which is a pity, because there is a dearth of published material for which the electrochemical replacement plating of silver has been presented. Depletion silvering was used in many of the silver-copper alloys, as expected, some with a base silver content as high as 76 percent, which is unusual for these types of silver-copper alloys. If depletion silvering and electrochemical replacement plating of silver have been used at the same site, it is more critical to present evidence for the latter, since otherwise there is insufficient evidence to determine that this is the necessary technique employed. The many axes and chisels in bronze carry evidence of use as tools. The authors make the point that for as long as bronze was used in the southern Andes, tin was the preferred alloying element, and may well have had special significance as an alloy in the Inca Empire. The T axes, which may have had ritual or symbolic significance, were the largest category of tool found at the site, but the items from Machu Picchu were actually used as artisans’ tools. These T-shaped axes cross cultural boundaries: the same form is found in pre-Roman contexts in Egypt and elsewhere. Shaping and fitting stone blocks was a major task for workers at Machu Picchu, so bronze pry bars and other tools would have been useful in exploiting natural bedding planes in granitic rocks. The metal microstructures of several of the tools record evidence of deformation caused by pounding on the tool with a hammerstone or by impact of the working edge of the tool with a hard material. This was an interesting finding of the present study. An apparently unique find is a llama-headed knife, which has a bronze blade surmounted by a cast-on head of a copper-bismuth-tin alloy with a distinctive color. The differences in liquidus or solidus temperatures in the copper-bismuth-tin system are not mentioned in the text, but one would imagine that the ternary alloy could have been chosen for this repair by casting-on because it had a lower melting point than the binary tin bronze and could therefore facilitate the use of the casting-on technique. Some further discussion of the lost-wax casting process would have been useful here in view of the fact that many of the artifacts were cast in bivalve molds. Multiple objects of the same size and shape could have been produced by using bivalve molds in clay taken from a master matrix.

In a very pertinent chapter, Bruce Owen discusses the meanings of metals from the site and notes the perspicacious work of Ambrosetti, who commented on the widespread evidence of intentionally destroyed axes, discovered throughout the Andes. In some cases, the upsetting of the bronze axe might be due not to unhafted use, as Gordon suggests earlier in the text of this book, but to intentional destruction of the axe by using blows against the back edge to flatten the working edge against a rock after removing the haft. Salazar has suggested that the metal objects at Machu Picchu were intentionally destroyed upon the death of the owner. Owen states that this is not the case and asks, if intentional destruction was not usually part of a mortuary ritual, then what was its purpose? This is not an easy question to answer, and Owen posits that a ritual explanation is still possible in most cases, but in contexts not directly connected to burials. A chapter well worth a careful read.

The metallographic work carried out in the past, a most useful compendium of information, has been added to recently with a number of color plates included in the book. These could have been better arranged to present two images per page rather than just one with a very large amount of white space at the bottom of each page; the 12 pages on glossy paper could have displayed 24 color photomicrographs instead of the current 11 (of which Plates 3 and 4 are out of focus). The accentuated segregation revealed by the use of Klemm's reagent needs to be discussed rather than presented in this context, since very different visual effects can be attained using alcoholic ferric chloride or Klemm's reagent with archaeological copper alloys, especially if augmented by partially plane-polarized light. Plate 4, for example, should have been manipulated in Photoshop to at least improve image sharpness, or might have been better left at a lower magnification. Plate 5, which is at moderate magnification, is also out of focus. ScaleJ, a free software download, could also have been used here to label the scale bars employed in the photomicrographs. It is difficult at present for metallographers wishing to take high-quality color photomicrographs who do not have $20,000–$50,000 to spend. The future will come to our rescue here by enabling the same quality of digital capture that we used to obtain with film—but what a cost that represents in 2016! In 2026–2036 it will be different.

In summary, this is a most valuable publication, which will serve as an important reference text on the metalwork from Machu Picchu. The text is accompanied by an extensive series of maps showing the geographic distribution of metallic artifacts, including tupus, T-shaped tumis, flat tumis, Guayas tumis, knives, chisels, and other tools, with a technical chapter of descriptions of selected artifacts from the site followed by a compendium of metal artifact technology. A good bibliography and index round out the book at a fairly reasonable price. It is delightful that research work begun in 1915 should have been brought to so successful a conclusion in 2015. In his long and brilliant poem, The Heights of Macchu Picchu, Pablo Neruda wrote:

Machu Picchu remains an iconic site in the human imagination. The humble tools of the craftsman, the metal axes and blades, the groundwork of labor, and the silver-copper ornaments examined in this book would have appealed to the Marxist philosophy of Pablo Neruda.