Macroscopically Non-Destructive Sampling Of Greenstone And Jadeitite Artefacts To Investigate Trade Routes Used By Caribbean Communities
As part of ‘NEXUS 1492’, a European Research Council funded “Synergy” project we aim to assess the impact of Caribbean colonisation on the indigenous (material) culture. Inter-Islands exchange networks present before and after the arrival of Columbus form an important focus of research within NEXUS 1492. Studies of lithic artefacts such as tools and beads play a key role in this respect as they provide essential information of the entire process of collection of raw materials, production of the artefacts, use of the artefacts, and distribution and trade by the pre-colonial communities.
Green stone and jadeitite artefacts are specifically useful as they have been recovered from archaeological excavations sites all over the Caribbean Archipelago, whereas the locations of (known) sources are limited to only few of the Islands (the Dominican Republic and Cuba) and mainland Guatemala. Finds of exotic greenstone materials on Islands in the Lesser Antilles suggest long distance inter-Island trade networks possibly even connecting to the Meso-American mainland. Chemical analyses of the artefacts and a comparison to the possible source rocks is the way to fully characterize the make-up of these trade routes. We have developed new techniques that allow us to perform chemical and isotopic analyses on micro gram amounts (~0.00001 g) of material from the artefacts to determine the source region of artefacts. Working with the Museo del Hombre Dominicano and Museo Altos de Chavon we have identified extensive collections of greenstone artefacts from archaeological sites across the Dominican Republic that we wish to sample to aid in understanding the production sites of greenstone artefacts and how they have been traded across the island and beyond.
We have a portable, macroscopically non-destructive, sampling device which allows us to visit collections present in museums to collect materials for the required chemical analyses. We guarantee that the sampling effort will not result in damage visible by the naked eye (see attached figures and accompanying video). With the proposed research we aim to determine 1) the exact sources of raw materials used to produce the artefacts, and 2) discover which settlements served as production sites and played key roles in the distribution of the materials to more distant Caribbean regions. On the longer term we expect to establish that the Dominican Republic was a key production and trading centre until well after the initial Colonial contact.
Greenstone is a common generic term for green-coloured metamorphic rocks that include jadeitite, greenschist, serpentinite, nephrite, chlorastrolite, chloromelanite and others. In the Caribbean greenstone has been primarily been used as raw material for the production of celts (axes) and adzes that were used as tools by the Pre-Colombian cultures of the Caribbean. More rarely, greenstones were used to make jewellery (beads) and figurines. Greenstone axes are the main target material for this study. Sampling of an axe artefact will be performed on broken rough surfaces to minimize potential disturbance of the original worked surfaces.
We aim to sample artefacts by ablating 100 µm spots on broken surfaces. The size of the ablation crater will be smaller than a sand grain and invisible to the naked eye (see Fig. 2). Collection of the ablated material will be onto filters that can be taken back to our labs for geochemical analyses. Sampling and analyses will be done by Dr. Janne Koornneef and Alice Knaf under supervision of Prof. Gareth Davies.
The portable laser device comes in a suitcase (55.3*42.4*27 cm) weighing 15 kg (Fig 1). The instrument consists of a pulsed solid state laser, an optical fibre attached to a hand-held module, a sampling filter mount and a membrane pump. The laser has an output wavelength of 532 nm (green light), which provides a pulse energy of 1.3 mJ and a pulse duration of < 1 ns. The ablation frequency can be varied between 10-2000 pulses per second (Hz). A typical sample is taken in a 1 minute routine at 100 Hz frequency (6000 pulses). The damage caused by the laser beam is an ablation crater with a diameter of 1/10 of a mm (100 µm, Fig 2). Artefacts may require multiple (max 3) samples to be taken for a fully representative analysis, depending on artefact type (mineralogy and grain size). The ablated material is transported by an air flow onto a filter. The filter wheel holder has 6 separate sample chambers. We expect to be able to sample 6 artefacts per hour.
Demonstration of macroscopic non-destructive sampling
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VU University Amsterdam, Faculty of Earth and Life Sciences, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands:
- Prof. Gareth R. Davies. Head of the Department of Geology and Geochemistry at the VU University Amsterdam since 2004 (firstname.lastname@example.org)
- Dr. Janne M. Koornneef. Post-doctoral researcher; 8 years research experience; specialised in isotope geochemistry technique development. (j.m. email@example.com)
- MSc. Alice C.S. Knaf. PhD student in NEXUS 1492 project since November 2013; subject lithic artefact provenance using isotope geochemistry (firstname.lastname@example.org)
Leiden University, Faculty of Archaeology, The Netherlands:
- Prof Corinne L. Hoffman. Dean of the Faculty of Archaeology since September 2013 and Professor of Caribbean archaeology and director of the Caribbean Research Group at Leiden University (email@example.com)
Museo Del Hombre Dominicano, Santo Domingo, Dominican Republic:
- Christian Martínez. General Director of the Museo del Hombre Dominicano since April 2010 (firstname.lastname@example.org)
- Dr. Jorge Ulloa Hung. Post-doctoral researcher, specialised in material culture, researcher of the Museo del Hombre Dominicano and lecturer of the Instituto Tecnológico de Santo Domingo, Post-doctoral researcher in NEXUS 1492 Project since September 2013 (email@example.com and firstname.lastname@example.org)
Museo Altos de Chavon, Casa de Campo, La Romana, Dominican Republic:
- Arlene Alvarez. Director of the Museo Altos de Chavon since 2000; PhD student in NEXUS 1492 project since September 2013 (email@example.com)
Project embedded within the ERC funded project ‘NEXUS 1492: Investigation of the impacts of colonial encounters in the Caribbean, the nexus of the first interactions between the New and the Old World.