Mid-Infrared (5-100 μm) Reflectance Spectra and Optical Constants of Ten Phyllosilicate Minerals

Timothy D. Glotch 
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91125
George R. Rossman, Oded Aharonson
Division of Geological and Planetary Sciences
California Institute of Technology,  Pasadena, CA 91125


We have derived the real and imaginary indices of refraction for 10 phyllosilicate minerals—montmorillonite, beidellite, nontronite, hectorite, saponite, illite, illite-smectite (60/40 interlayered) kaolinite, halloysite, and serpentine—from 100-2000 cm-1 (5-100 μm) at 2 cm-1 spectral sampling using classical Lorentz-Lorenz dispersion theory. We present the real and imaginary indices, and the oscillator parameters with which they were modeled. Use of these optical constants will aid in the modeling of thermal infrared spectra of planets, asteroids, interplanetary and interstellar dust, and protoplanetary disks around nearby stars.

Data Files from the paper are now available at   http://aram.ess.sunysb.edu/tglotch/optical_constants.html
Dioctahedral Smectites:
Montmorillonite SWy-1
Beidellite SBId-1
Nontronite NAu-1
Trioctahedral Smectites:
Hectorite SHCa-1 
Saponite SpNv-1 
Illite/Illite-Smectite Group:
Illite IMt-1    
Illite-Smectite ISMt-1 
Kaolinite Group:
Kaolinite KGa-1
Halloysite HWw-1
Serpentine Group:
Serpentine BUR-1690 (Antigorite)
Cronstedtite 112792   

Icarus 192, 605-622