Research Interests
Although my background is in crystal chemistry, my work has expanded to cover three main areas of mineralogy: crystal chemistry, granitic pegmatites, and the geology of gem deposits.
I became interested in mineralogy after taking a course in X-ray crystallography. In the world of crystal chemistry I am probably best known for my work on vesuvianite, a common mineral with chemistry and structure that is both complicated and variable. I am currently studying the borosilicate minerals dumortierite and holtite. I am concentrating primarily on correlations between chemical composition, crystal structure, morphology and conditions of formation.
I have also worked on the crystal chemistry and mineral physics of the isostructural minerals titanite (CaTiSiO5), malayaite (CaMnSiO5), kieserite (MgSO4·H2O), and the amblygonite (LiAlPO4F)-montebrasite (LiAlPO4OH) solid solution. The crystal chemistry of oxysalt minerals containing heavy elements (e.g., tellurium, barium, mercury, and lead) has also been one of my research priorities. These minerals have been poorly studied in the past because of analytical problems associated with heavy atoms. Tellurium-oxysalt minerals are very interesting because of the presence of Te4+ (with lone-pair electrons) and/or Te6+. The Hg-oxysalt minerals are worthy of study as a result of the presence of Hg+ (in dimers) and/or Hg2+.
One of the reasons I became a geologist was that I enjoy working in the outdoors. Before starting graduate school I had summer jobs in exploration geology in British Columbia, the Yukon, and Labrador. When I came to UBC I initiated a study of granitic pegmatites in the Canadian Cordillera. Since the early 1990s I have been studying the Little Nahanni Pegmatite Group, a 15 km long swarm of nearly continuous pegmatites in the southwestern Northwest Territories. Our work has shown that the pegmatites are enriched in lithium, niobium, tin, and tantalum. Ongoing research includes dating, stable isotopes, fluid inclusions, mineralogy, whole rock and mineral chemistry, and contact and regional metamorphism. We have also studied the O’Grady aplite-pegmatite complex (also in the Northwest Territories) and the Taylor 2 pegmatite in northern Ontario, with its attendant emerald occurrence. I am currently working on grantitic pegmatites in the central Yukon and British Columbia. A recent interest is the geochemistry of tungsten deposits, and a study of the mineralogy, geochemistry, and geochronology of Northern Dancer, one of the world’s largest tungsten molybdenite systems, is nearing completion.
I became interested in the geology of gem deposits after recognizing that most are rare because the necessary geologic conditions are seldom attained. These exceptional requirements also make gem deposits fascinating for scientific study. My research to date has concentrated on emerald and sapphire occurrences in Canada and the United States. In 2007 I edited a volume on the geology of gem deposits, and in 2008 I published a comprehensive review of emerald deposits and occurrences. One of the things I am most interested in is how scientific research can aid exploration, which until recently has been non-systematic and, in many cases, nonexistent for any gem mineral except diamond.
I have also done some work in environmental mineralogy and geomicrobiology which continues to this day.
Much of my research is done in collaboration with others at UBC, within Canada, and around the world.