American Museum of Natural History Research Library
author: American Museum of Natural History

Webster, James D.
James D. Weber is a Curator at the American Museum of Natural History, Department of Earth and Planetary Sciences, Division of Physical Sciences and a Professor in the Richard Gilder Graduate School. He joined the museum in 1990 researching ore deposits, specifically ones associated with underground magmas and volcanic flows and was an Assistant Curator in the Department of Mineral Sciences.
Dr. Webster investigates how the volatiles water, fluorine, chlorine, sulfur, and carbon dioxide influence how magmas evolve chemically; how they control the formation of metallic ore deposits; and how they impact volcanic eruptions. He investigates how ore deposits are generated through late-stage hydrothermal and mineralizing processes in magmas. Dr. Webster also studies the influence of volatiles on the melting behavior and stability of minerals, and how and when magmatic-hydrothermal fluids are released from magma. This research involves study of silicate melt inclusions, which are microscopic inclusions of silicate melt trapped in minerals from mineralizing and/or erupting magmas. To assist in this research, he has recently constructed a Vernadsky-style heating stage for observing silicate melt inclusions, with a microscope, while they are melted at high temperatures. He is presently working on hydrothermal experiments involving apatite, silicate melts, and volatile-rich fluids to better understand magmatic processes. With scientists from the University of Hannover, Germany, he is developing a model to compute Cl solubilities in silicate melts. Other research – with museum colleagues – on sulfur, chlorine, carbon dioxide, and water provides information on the nature of gases released during explosive volcanism at Augustine volcano, Alaska, and Dr. Webster has recently begun a new study on sapphire- and spinel-bearing metamorphic rocks of the Mogok region of Myanmar. (AMNH web site, 2017)