VISIBLE AND NEAR-INFRARED SPECTRAL SURVEY
OF NIPR METEORITE CHIP SAMPLES.
T. Hiroi1, H. Kaiden2, N. Imae2, A. Yamaguchi2, H. Kojima2, andS. Sasaki3. 1Brown University (takahiro_hiroi@brown.edu),
2
National Institute of Polar Research, 3Osaka University.
Introduction: Visible and near-infrared (VNIR) reflectancespectroscopy is highly useful for characterizing the mineral composition of solid planetary materials such as meteorites. Especially, measuring individual clasts on the surface of meteoritechips could identify end-member minerals and their spectra,
which will be highly useful in identifying rock types and theirformation and evolution. In June 2010 we started a VNIR spectral survey of meteorite samples stored at the National Institute ofPolar Research (NIPR) and finished those for lunar, Martian [1],and HED meteorite samples. Then, we began surveying carbonaceous chondrite (CC) samples in November 2012.
Experimental: Meteorite chip samples stored at NIPR having fresh, naturally-broken surface were identified through prescreening based on their catalog and visual examination. Bidirectional VNIR diffuse reflectance spectra of one or more spots
on each chip sample were obtained at every 5 nm over the wavelength range of 0.25-2.5 µm at either the RISE Project of the National Astronomical Observatory of Japan (NAOJ) or Osaka University. A detailed description of the procedure is given in a
separate paper [1]. For this study, incident beam size was about
3×2 mm. In addition, biconical Fourier Transform infrared(FTIR) reflectance spectra of those spots were measured at 4 cm-1
resolution over the wavelength range of 1.7-25 µm at RELAB, aNASA multiuser facility [2]. The FTIR spectra were scaled toconnect with the VNIR spectra at 2.5 µm. So far, 116 meteorite
samples have been measured.
Results: Martian meteorite chip surfaces looked highly homogenous as we reported [1] and derived mineralogy of eachsample was consistent with previous studies. Clear plagioclase
spectral features, especially the 1.25 µm absorption band wasidentified on lunar HED meteorite chips. Linear extrapolationand modified Gaussian model (MGM) [3] deconvolution weresuccessfully performed on the spectra to derive end-member mineral spectra or the band parameters [4]. Carbonaceous chondrite
types and diversity of CM chondrites were successfully recognized, including those thermally metamorphosed and having unusual 3 µm band shape [5].
Conclusions: It has been successfully proven that VNIR reflectance spectral measurements of millimeter-size spots on naturally-broken meteorite chip surfaces can produce useful information on their mineralogy. This method is especially useful for theclassification and mineralogical characterization of meteorites inboth the laboratory and planetary landing missions.
References: [1] Hiroi T. et al. 2011. Polar Science 5:337344. [2] Pieters C. M. and Hiroi T. 2004. Abstract #1720. 35thLunar & Planetary Science Conference. [3] Hiroi T. et al. 2012.
Abstract #1168. 43rd Lunar & Planetary Science Conference. [4]Sunshine J. M. et al. 1990. Journal of Geophysical Research
95:6955-6966. [5] Hiroi T. et al. 2014. Abstract #1106. 45th Lunar & Planetary Science Conference.

Acknowledgment: This research was partially supported by JSPS Grant-in-Aid for Scientific Research (C)and NASA SSERVI.