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MEI Online: Commodities: Non-Metallic Ores: Diamond: Latest News: Feb.10, 2009


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:: Mintek, SADPMR Launch Diamond Fingerprinting Project

Mintek, South Africa’s national mineral research organisation and a global leader in mineral and metallurgical innovation, and the SA Diamond and Precious Metals Regulator (SADPMR) have launched a project to study the possibilities of determining the origin of rough diamonds. The study is aimed at ascertaining whether trace element analysis can be used in combination with physical characteristics to link diamonds to their source, particularly in the case of illicitly traded stones.

The heart of the project is a new laboratory facility in Mintek's Mineralogy division, funded by the SADPMR and equipped with a state-of-the art Laser Ablation Inductively Coupled Plasma Mass Spectrometer (LA-ICP-MS) which is capable of analysing more than seventy elements at sub-parts-per-billion and lower levels.

This laboratory is the first of its kind in Africa, and one of very few such facilities world-wide. Commissioning was completed in November 2008 and method development is underway.

"If proven to be successful, diamond fingerprinting would help to reduce theft and illegal mining and assist in preventing 'conflict diamonds' from entering the legitimate trade", said Ashok Damarupurshad, strategist at the SADPMR. "That is the objective of the Kimberley Process Certification Scheme, and it is for this reason that the SADPMR has provided the initial funding to establish the laboratory at Mintek."

Although diamonds from sources world-wide will be analysed, the study will focus on southern African countries, and particularly on diamonds from alluvial sources, which are less easy to regulate than "hard-rock" mining operations.

"Alluvial fields may contain diamonds from many different primary sources", said Amanda Quadling, manager of Mintek's Mineralogy division. "Although this complicates provenance studies, we felt the need to home in on the central area of concern regarding trade in illicit/conflict diamonds. This approach gives us a unique R&D angle relative to other similar projects. Also, profiling the multi-feed nature of an alluvial deposit might be a useful goal in its own right."

"This project will provide a new platform for skills development in South Africa", said Dr Molefi Motuku, Mintek's General Manager: Research and Development. “The Department of Minerals and Energy (DME) and the Regulator are strongly encouraging local research into the broad topic of diamond fingerprinting, which other major diamond-producing countries have been investigating for some time."

Leading the development of the fingerprinting method is independent consultant on the project, Dr Sonal Rege-Delpech, who was awarded her PhD in the subject by Macquarie University in Australia. "Diamonds are a highly pure form of carbon, and their very strong lattice structure makes it difficult for the crystal to incorporate impurity atoms," she explained. "Our research will be focusing on the trace element analysis of sub-microscopic fluid/solid inclusions that represent diamond-forming fluids, characteristic to the different source regions. We will combine this geochemical information with basic morphological, colour, inclusion and FTIR data and use multivariate statistical methods to try and assign unique characteristics to diamonds from particular deposits."

Mintek is aiming to eventually establish a comprehensive database of southern African alluvial diamond types. Ownership of this database would vest with SADPMR, taking account the inherent ownership of data that each of the diamond sample providers will be entitled to. Mintek will, through the DME, approach other SADC countries around possible collaboration on the supply of samples and sharing of data, and all expressions of interest from other African countries with respect to this project are welcome.

What is diamond fingerprinting?

Diamond fingerprinting refers here to geochemical fingerprinting of individual diamonds for the purposes of discriminating between diamonds from different mines or deposits on the basis of their trace element chemistry. Essentially diamond fingerprinting seeks to identify the origin of a diamond by comparing its trace element chemistry to profiles for different sources.

How is geochemical fingerprinting undertaken?

Scientist use ultra-sensitive techniques such as Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) in conjunction with a data processing statistical model, to generate profiles corresponding to trace and minor element distributions in diamonds. If these profiles are proven to be unique for different sources it would allow for provenance studies. Before it can work, though, a comprehensive database containing the fingerprints of the world's diamonds would have to be gathered.




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