Jack Voncken (1959) studied Geology at Utrecht University, the Netherlands. In 1984 he passed his “Doctoraal Examen” (equivalent to an MSc) in Geology with a major in (Igneous) Petrology and minors in Exploration Geochemistry and Economic Geology. After graduating he conducted PhD research, also at Utrecht University, on the synthesis, characterization and crystallography of two rare ammonium-aluminum-silicates (buddingtonite, NH4AlSi3O8, and tobelite, NH4Al2Si3AlO10(OH)2) and their Rb-and Cs-analogues.  He obtained his PhD in 1990 at Utrecht University with a thesis entitled “Silicates with Incorporation of NH4+, Rb+ or Cs+ ”.   Between 1988 and 1990, he was employed at Twente University of Technology, Enschede, the Netherlands, where at the Inorganic Materials Science section of the Faculty of Chemical Technology he developed a method for measuring drying stresses in thin drying gel coatings.  In 1990 he joinedDelft University of Technology. He started at the Faculty of Mining and Petroleum Engineering, in the Raw Materials Technology (later called Resource Engineering) section, as an assistant professor for Mineralogical Aspects of Raw Materials. From 2006 until 2011, after the discontinuation of the Resource Engineering section, he worked in the Applied Geology section. After the re-establishment of the Resource Engineering section in 2011, he returned to that group, again as an assistant professor. The Faculty of Mining and Petroleum Engineering merged with the Faculty of Civil Engineering in 2007 to form the Faculty of Civil Engineering and Geosciences.  Jack Voncken’s specialties lie in Economic Geology, in Ore Minerals and Industrial Minerals, and in analytical techniques and characterization techniques for minerals and rocks. Given his interest in Ores and Industrial Minerals, he has also focused on Rare Earth Elements since 2009.

• 1. The Rare Earth Elements – a special group of metals.- 2. The Ore Minerals and Major Ore Deposits of the Rare Earths.- 3. Physical and Chemical Properties of the Rare Earths.- 4. Mineral Processing and Extractive Metallurgy of the Rare Earths.- 5. Applications of the Rare Earths.- 6. Economic Aspects of the Rare Earths.- 7. Recycling of Rare Earths.

"This exceptionally well-written, compact, balanced, and highly informative work is primarily designed for the well-educated scientist/engineer and moderately technical economist. ... Numerous end-of-chapter references, charts, tables, and graphs support the text. ... it is an essential volume for the advanced student and general professional interested in the science, engineering, and economics of rare earth metals. Summing Up: Highly recommended. Upper-division undergraduates through professionals/practitioners." (T. L. T. Grose, Choice, Vol. 53 (11), July, 2016)