Spectra of Shock-Affected Rhodonite: A Reply

Rex V/ Gibbons
  Geology and Geophysics Branch
NASA - Johnson Space Center
  Houston, Texas 77058

Thomas J. Ahrens, George R. Rossman
 Division of Geological and Planetary Sciences
California Institute of Technology
Pasadena, CA  91125


The Gaussian resolution procedure of Faye (1975) leading to the conclusion that the spectral changes in a shock-loaded rhodonite are the result of a broadening or intensification of the ultraviolet charge-transfer absorption and that the 540 nm band is present with comparable intensity in both pre- and post-shock samples is not physically meaningful because it has ignored the dominant process which gives rise to the rising baseline "absorption" throughout the near-infrared and visible spectral regions. That process is wavelength-dependent scattering.

Scattering Spectrum
Optical absorption spectrum of a rhodonite sample 0.31 mm thick recovered from a 496 kbar shock (solid line). The
dotted line is the scattering curve of abraded glass plates which illustrates the wavelength dependence of scattering.

last updated: 26-Jul-2023