Pre-Columbian alloys from the royal tombs of Sipán and from the Museum of Sicán (original) (raw)
Archeosciences Revue D Archeometrie, 2009
Pre-Columbian alloys from the royal tombs of Sipán and from the Museum of Sicán », ArcheoSciences [Online], 33 | Abstract: On the north coast of present-day Peru, approximately between 50 and 700 AD, flourished the Moche civilization. It was an advanced culture, and the Moche were sophisticated metalsmiths. The Moche metal working ability was impressively shown by the excavations of the "Tumbas Reales de Sipán", discovered by W. Alva and co-workers in 1987. The Sicán culture is a successive civilization (750-1375 AD) which extended as far as present day Piura in the north and Trujillo in the south. The Sicán culture was strongly influenced by the Moche culture, particularly in its metallurgical development . The metal objects from the Museums of Sipán and Sicán were analyzed with a portable equipment which uses energy-dispersive X-ray fluorescence (XRF). This portable equipment is composed of a small size X-ray tube and a Si-PIN thermoelectrically cooled X-ray detector. It was determined that the analyzed artefacts are composed of gold, silver and copper alloys, of gilded copper, of silvered gold, and of tumbaga, the last being a poor gold alloy enriched at the surface by depletion gilding, i.e. removing copper from the surface. In the case of gold, silver and copper alloys, their composition was determined by EDXRF analysis employing standard alloys. In the case of gilded copper, silvered copper and of tumbaga, the ratio Cu(Kα/Kβ) was accurately determined from the X-ray spectra, first in order to clearly distinguish them, and subsequently in order to determine the thickness of the gilding. Mean values of 0.4 μm and 2.7 μm were determined for gilded copper and tumbaga, respectively. For gilded silver, the ratio Ag(Kα/Kβ) was measured. The ratios Au-Kα/Cu-Kα, Ag-Kα/Cu-Kα and Au-Kα/Ag-Kα (gilded copper, silvered copper, and gilded silver, respectively) also depend on the thickness of gilding or silvering, and were employed to this aim.
MRS Proceedings, 1995
The Sicdn Archaeological Project (under the direction of I. Shimada) is centred in the Bat~.n Grande region of the La Leche Valley in northern Peru. One of the major topics of investigation is Middle Sicin (A.D. 900-1100) metallurgy within its broader cultural and environmental contexts. Results of the investigation of copper-arsenic alloy production have been published [1,2]. Two major Middle Sicdn elite tombs excavated during the 1991-2 season yielded large quantities of diverse precious metal and arsenical copper objects. In particular, the twelve-metre deep shafttomb at the north base of the pyramidal temple of Huaca Loro contained some 1.2 tons of grave goods with about 75% of them in weight being metal [3-6]. Samples of precious metal artifacts are being studied using metallographic techniques and electron probe microanalysis (EPMA). At this stage of the investigation, over 40 samples of gold-silver-copper alloy, sheet-metal objects have been analyzed using over 200 EPMA data points on depletion gilded surfaces and multiphase compositions of the centres. The metallographic structures of the objects are extensively coldworked, but variable in composition including single and multiphase alloys. Surface enrichment is characteristically on the order of 10-20 microns, but several examples are observed with greater thickness. Depletion gilding is documented even in some of the most corroded metal samples. Object types studied include crowns, headdresses, "feathers", hanging ornaments, wire and foil as well as several exceptional objects. Additional analyses are presented for a gold-silver-copper alloy ingot and standardized copper-arsenic alloy objects called naipes. Due to the archaeological significance of this assemblage of artifacts as well as the quantity, there are several research groups working cooperatively , using different analytical techniques. Compositional results are used to explore issues such as selection of precious metal alloys by surface colour and mechanical properties.
Metallurgical case studies from the British Museum`s collections of pre-hispanic gold
Boletin Museo Del Oro, 1998
Warm es t thanks are du c to Professor jcan Thomas, Co lm Mc Ewan , N 1gc l Mce ks , Shcn dan Bowman and john Mack tlt the Bnti sh Museum ; lO Cleme nc ia Pla zas, So ma Arc hlla , Juamta Sáenz, Luz Alba Gómez, and all thc staff at thc Museo del Oro, Bogota ; tO Warwic k Bray, lns uuue of Archaeology, Umvc rs•ry Collcgc, London ; Patncia E.stévcz, Banco Central del Ecuador ; Cec1ha Bakula, Banco Centra l de Reserva del PerU and Paloma Ca rcedo de Mufarcch 1 am espcc•ally gratcful to t.he Royal Socte ry of Great Brna1n for a research travcl grane Also to The H1 storical Mctall urgy Soc1e ty for a contri button to conferencc expenses.
X‐Ray Spectrometry, 2008
nuFrom the study of coins and casted simple objects to intricate jewellery comprising many diverse parts joined together, analytical queries on ancient goldwork concern the description of the manufacturing techniques, the identification of the authenticity and the localisation of the exploited sources of gold. Through the examination of the objects by x-ray radiography and the non-destructive elemental analysis of the gold alloys – by XRF, SEM-EDX, PIXE and SR-XRF, x-ray based techniques have always played an important role in the study of cultural heritage and, in particular, of goldwork. The aim of this article is to give a short overview of the use of the most established scientific-based techniques in the study of goldwork, with special outlining on the limitations, advantages and applications of x-ray based techniques. Two applications illustrate both the potential of examination techniques to identify the authenticity of gold jewellery and the importance of combining examination techniques and elemental analysis to describe the fabrication stages of goldwork. At last, a third example shows the significant socio-economical assumptions developed by determining the characteristic trace elements of gold when coinages are considered.
2018
1 Università di Sassari, Sassari, Alghero, Italy 2 Universidad Nacional Mayor de San Marcos, Lima, Perù 3 PACEB Museo Cao e Fundacion Wiese, Trujillo, Perù 4 COPPE, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil 5 Museo “Tumbas Reales de Sipán”, Lambayeque, Perù 6 Museo de sitio Huaca Rajada, Sipán, Lambayeque, Perù 7 Dipartimento di Chimica e Farmacia, Università di Sassari, Sassari, Italy 8 Dipartimento di Scienze di base ed applicate per l’ingegneria, Università di Roma “La Sapienza”, Rome, Italy 9 Arsmensurae, Rome, Italy
Analysis of the spectacular gold and silver from the Moche tomb 'Señora de Cao'
On the north coast of present-day Peru, between the Andes and the Pacific Ocean, approximately between 100 and 600 AD, the Moche civilization prospered. The Moche were very sophisticated artisans and metal smiths, so that they are considered the finest producers of jewels and artifacts of the region. Their metalworking ability was impressively demonstrated by the excavations of the tomb of the 'Lady of Cao' (dated around third–fourth century AD) discovered by Regulo Franco in 2005. Impressive is the beauty of the artifacts, and also the variety of metallurgical solutions, demonstrated by not only the presence of objects composed of gold and silver alloys but also of gilded copper, gilded silver, and tumbaga, a poor gold Cu-Au alloy subject to depletion gilding. About 100 metal artifacts from the tomb of the Lady of Cao, never before analyzed, were studied by using various portable equipments based on following non-destructive and non-invasive methods: • energy-dispersive X-ray fluorescence with completely portable equipments; • transmission of monenergetic X-rays; • radiographic techniques; and • optical microscopy. Gold objects and gold areas of nose decorations are characterized by approximately the same composition, that is, Au = (79.5 ± 2.5) %, Ag = (16 ± 3) %, and Cu = (4.5 ± 1.5) %, while silver objects and silver areas of the same nose decorations show completely erratic results, and a systematic high gold concentration. Many gilded copper and tumbaga artifacts were identified and analyzed. Further, soldering gold–silver was specifically studied by radiographs. Additional measurements are needed, particularly because of the suspect that depletion gilding was systematically employed also in the case of some nose decorations.
A microstructural study of gold treasure from monte alban’s Tomb 7
JOM, 2005
This article presents a microstructural study of a set of samples from the treasure of tomb 7 of Monte Alban, Oaxaca, in southeast Mexico. The purpose of this work was to elucidate the manufacturing methods used by the pre-Columbian artisans of the Oaxaca valley. An additional goal was to establish a point of comparison between Mesoamerican cultures and cultures in some other regions of the Americas. Ten gilt samples were analyzed corresponding to the post-classic period (700-1300 A.D). The microstructure and elemental composition of the samples were determined using optical, scanning, and transmission-electron microscopies and electron-energy-dispersive spectroscopy. The samples were classifi ed by the method of manufacture. A predominant use of gold alloys was found, rather than the gilt copper commonly used by some cultures in South America.