The Sheahan Diamond Literature Reference Compilation is compiled by Patricia Sheahan who publishes on a monthly basis a list of new scientific articles related to diamonds as well as media coverage and corporate announcements called the Sheahan Diamond Literature Service that is distributed as a free pdf to a list of followers. Pat has kindly agreed to allow her work to be made available as an online digital resource at Kaiser Research Online so that a broader community interested in diamonds and related geology can benefit. The SDLRC Blog is a guest commentary by an industry expert about articles, themes and trends in recent issues of the SDLRC.
Comments by Brooke Clements
Brooke Clements received a B.Sc in Geology from Indiana University and an M.Sc in Economic Geology from the University of Arizona. From 1982 to 1997, he was an Exploration Geologist and Regional Manager for Exmin Corporation where he conducted diamond exploration programs throughout the United States. From 1998 to 2007 he was Vice President, Exploration for Ashton Mining of Canada Inc. Under his leadership, the Ashton-SOQUEM exploration team discovered the Renard diamond district in Quebec where Stornoway Diamonds opened the Renard Diamond Mine in 2016. From 2007 to 2015 he was President of Peregrine Diamonds Ltd. where he led the team that discovered the Chidliak diamond district on Baffin Island in the Canadian Arctic. Currently, Brooke is President of JBC Ventures Ltd., a consulting company specializing in mineral exploration and community and government relations. He is also President and CEO of Craton Minerals Ltd., a private diamond exploration company focused on discovering North America's next new diamond district.
Brooke Clements has volunteered to highlight the scientific articles that caught his attention in the monthly reference compilations. The opinions expressed are solely his and he can be reached at .
Winter 2019 Issue of Gems and Gemology focused on geographic origin of colored gemstones: Knowing the geographic origin of a colored gemstone is an important factor for those making an expensive purchase. Pat references a number of papers in the winter 2019 issue of Gems and Gemology devoted to the geographic origin of colored gemstones. The issue is a free download. An introductory paper makes the point that it is virtually impossible to determine with 100% certainty the source area of a colored gemstone but experienced experts with access to modern laboratory techniques can make good prognostications. A paper by Giuliani and Groat summarizes the geology of corundum and emerald gem deposits. A paper by Groat et al. summarizes the lab techniques used to pinpoint gemstone source areas. There are also papers on the geographic determination of sapphire, ruby, emerald, tourmaline and alexandrite.
The first 19 pages of this volume on the mineral resources of India are devoted to diamond/kimberlite/lamproite deposits. There is a concise tabulation of important localities throughout the country. Before the discovery of diamonds in Brazil in 1825, India was it. A number of famous stones have come from there including the 67 ct. Hope Diamond which is housed in the Smithsonian. Most diamond source rocks are located in three provinces. Secondary diamond deposits in southern India have been traced back to conglomerate formations of several ages.
Prior to its closing, the Ellendale Mine in Australia produced about 50% of the world's yellow gem diamonds. Recent recoveries of yellow diamonds from the Ekati Mine in the Northwest Territories, the CH-7 pipe at Chidliak and the Naujaat project in Nunavut have fuelled speculation that Canada could one day become a significant producer of fancy yellow diamonds. This paper describes detailed testing of diamonds from Ekati and Chidliak that have colorless cores and yellow outer layers indicating episodic growth of the diamonds. I found the following conclusion from the paper fascinating: "Based on their nitrogen characteristics, both the yellow diamonds and yellow rims must have crystallized in close temporal proximity (<<1 Ma) to kimberlite activity at CH-7 and Misery".
Fresh hypabyssal and pyroclastic kimberlite samples from the A154 North and South kimberlite pipes at Diavik were studied in an effort to understand the processes responsible for the explosive kimberlite magmatism there. They conclude that "controls on kimberlite explosivity at Diavik are likely due to external factors, such as local stress regimes, the availability of groundwater (i.e. phreatomagmatism) and differing magma supply rates".