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George R. Rossman

Professor of Mineralogy
B.S., Wisconsin State University, 1966; Ph.D., Caltech, 1971. Instructor, Caltech, 1971; Assistant Professor, 1971-77; Associate Professor, 1977-83; Professor, 1983-2008; 2015-; McMillan Professor, 2008-15; Divisional Academic Officer, 1999-2008.
Research Summary
Spectroscopic methods applied to minerals which address trace hydrous components, metal ion site occupancy, color, ionizing radiation effects, nano-phases and X-ray amorphous materials. Caltech Mineral Spectroscopy Server

Research Options

Geochemistry;  Geology; 

Research Areas

Environmental Geochemistry;  Mineralogy; 

Profile

Mineralogy

A major focus of attention is the relationship between the spectroscopic properties of minerals and their composition and structure. Topics include trace hydrous components in minerals, metal ion site occupancy, effects of natural ionizing radiation, and X-ray amorphous materials.
Click here for more information on Mineralogy at Caltech.

Hydrous Components in Nominally Anhydrous Minerals

Hydrogen is one of the most pervasive elements in the crust and upper mantle of our planet. It is a mobile, reactive component which can cause major changes in the chemical, physical, rheological, and electronic properties of the host phase. Much of the effort of our group is directed at investigating the possibility that hydrogen, in some chemical form (typically OH- and H2O), can enter the structure of major minerals which are usually formulated as anhydrous. These studies rely heavily upon spectroscopic methods of analysis because they can determine both the chemical species present and, with proper calibration, the amount of hydrogen present. ... more ...

Spectroscopy of Minerals

Spectroscopic probes ranging in energy from gamma rays to microwaves play an important role in contemporary mineral studies. They are used to identify the cations which are present in a mineral, their concentration, their crystallographic site, and the identity of ions in the immediate vicinity of the target ion. Our students and postdocs have played a prominent role in the development and application of these methods. Special attention is directed at systems where the spectroscopic response is not proportional to the sum of the response of the individual components. Intervalance charge transfer processes which involve two or more cations which can exist in different oxidation states are most important. The Fe2+ - Fe3+ and Fe2+ - Ti4+ interactions, which are particularly important in establishing the color of many common minerals such as micas, amphiboles, and pyroxenes, have been the object of much research.

Radiation-induced DamageRead More

Publications

Please see George Rossman's publications page:

http://minerals.gps.caltech.edu/manuscripts/Index.html

Ge 114 a. Mineralogy. 6 (3-0-3); first term, 2023-24. Atomic structure, composition, physical properties, occurrence, and identifying characteristics of the major mineral groups.
Instructor: Rossman
Ge 114 b. Mineralogy Laboratory. 3 units (0-3-0); first term, 2023-24. Laboratory work involving the examination, characterization and identification of important minerals by their physical properties.
Instructor: Rossman
Ge 114. Mineralogy. 9 units (3-4-2); first term, 2022-23. Atomic structure, composition, physical properties, occurrence, and identifying characteristics of the major mineral groups. The laboratory work involves the characterization and identification of important minerals by their physical properties.
Instructor: Rossman
Ge 114 a. Mineralogy. 9 units (3-4-2); first term, 2021-22. Atomic structure, composition, physical properties, occurrence, and identifying characteristics of the major mineral groups. The laboratory work involves the characterization and identification of important minerals by their physical properties.
Instructor: Rossman
Ge 114 b. Mineralogy Laboratory. 3 units (0-2-1); first term, 2021-22. Prerequisites: concurrent enrollment in Ge 114 a or instructor's permission. Additional laboratory studies of optical crystallography, the use of the petrographic microscope, and optical methods of mineral identification. Not offered 2021-2022.
Instructor: Rossman
Ge 116. Analytical Techniques Laboratory. 9 units (1-4-4); second term, 2021-22. Prerequisites: Ge 114 a or instructor's permission. Methods of quantitative laboratory analysis of rocks, minerals, and fluids in geological and planetary sciences. Consists of five intensive two-week modules covering scanning electron microscopy (imaging, energy-dispersive X-ray spectroscopy, electron backscatter diffraction); the electron microprobe (wavelength-dispersive X-ray spectroscopy); X-ray powder diffraction; optical, infrared, and Raman spectroscopy; and plasma source mass spectrometry for elemental and radiogenic isotope analysis. Satisfies the Institute core requirement for an additional introductory laboratory course.
Instructors: Asimow, Jackson, Rossman
Ge 214. Spectroscopy of Minerals. 9 units (3-0-6); third term, 2021-22. Prerequisites: Ge 114 a, Ch 21 ab, or instructor's permission. An overview of the interaction of minerals with electromagnetic radiation from gamma rays to microwaves. Particular emphasis is placed on visible, infrared, Raman, and Mössbauer spectroscopies as applied to mineralogical problems such as phase identification, chemical analysis, site populations, and origin of color and pleochroism. Given in alternate years; not offered 2021-2022.
Instructor: Rossman