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Clark et. al. 2003 USGS Open File Report 03-395
Spectral Library splib05a Sample Description

(For further information on spectrsocopy, see: http://speclab.cr.usgs.gov)

TITLE: Lepidocrosite GDS80 (Syn) DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: GDS80

MINERAL_TYPE: Hydroxide

MINERAL: Lepidocrosite (Synthetic)

FORMULA: gamma-FeO(OH)

FORMULA_HTML: gamma-FeO(OH)

COLLECTION_LOCALITY: Synthetic, Dave Sherman

ORIGINAL_DONOR: Dave Sherman

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

Polymorphous with Akaganeite, Feroxyhyte, and Geothite.

"This sample was synthesized by aerial oxidation of a FeCl2 solution at a pH or 6-7. The X ray diffraction pattern of this sample was extremely well-defined, implying a high degree of crystallinity."

The above description may apply to this sample. This sample was one of a series of samples made for the following paper:

Sherman, D.M., R.G. Burns, and V.M. Burns, 1982, Spectral characteristics of the iron oxides with application to the Martian bright region mineralogy. Journal of Geophysical Research, v. 87, n. B12, pp. 10169- 10180.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

40 kV - 30 mA, 7.3-9.5 keV
File: lepicr80.out, -.mdi
Reference: JCPDS #8-98, 29-713
Found: lepidocrocite and goethite in subequal proportions
Sought: quartz (see comment)

Comment: Poorly crystallized: weak, broad reflections for both oxides. The goethite (110) and lepidocrocite (120) reflections are in the positions of the quartz (100) and (101) reflections and would prevent X-ray powder detection of a small amount of quartz, if present.

J.S. Huebner, J. Pickrell, T. Schaefer, written communication 1994, Reston, VA.

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EM(WDS), ICP(Trace), WChem
COMPOSITION_TRACE:

COMPOSITION_DISCUSSION:

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

Because the spectra of lepidochrosite is expected to resemble that of goethite it is unknown to what extent the goethite contaminant spectrally interferes with the lepidochrosite spectral features in this sample. G. Swayze

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1?2_3_4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns

LIB_SPECTRA_HED: where Wave Range Av_Rs_Pwr Comment
LIB_SPECTRA: splib04a r 2727 0.2-3.0µm 200 g.s.=
LIB_SPECTRA: splib05a r 4099 0.2-3.0µm 200 g.s.=


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